IBC Symptoms?? What do I need to know?

Hi everyone,
I am here to ask some questions because I had some strange symptoms last weekend and after doing some online research (which my husband always warns me about) I'm more than a little worried about the possibility of IBC.

A little background: I'm 43 years old, have breastfed two kids (one of which is 20 months old and I'm still breastfeeding, but only first thing in the mornings and before bed) and I have had mastitis twice in the last 18 months, which I did not take meds for, but treated with supplements, cabbage leaves and heat compresses. I am 5'2" and weigh 130 pounds. I have not been on the pill since 2006 and I had a mammogram at 40 (the 1st and last ) and all was clear.

So this is what happened;
On Saturday night (3 days ago) I noticed that my left breast was a bit larger than my right. Now, I should mention that while I was breastfeeding on a more regular basis, my left breast would always be the larger of the two especially if I hadn't nursed for a few hours. But that night while watching tv, I looked down and noticed that my left breast was bulging out of my bra and I just kinda thought 'hmmm...that's odd, that hasnt happened for a while'. Didnt think much of it but by the time I went to bed, I was feeling achey and flu-like and my left breast was really swollen and hot (I looked in the mirror before I got in bed and the whole top right quarter of my breast was red and hot to the touch). So I went to bed, feeling really crappy, thinking I was getting mastitis again and then while in bed I was absolutely freezing! We live in California and I don't run the AC at night so it's warm at night, but I could not get warm. I ended up getting out of bed to find some socks and even wrapped my socked feet in a flannel pillowcase to get them warm. I could not sleep I was so achey and cold, and I also had gotten some heat packs to put on my left breast cuz by this time it was really hurting. I finally woke up my son and let him nurse (which he does not get to do usually) on that side to try and relieve some of the pressure.
At 4am, I went to the medicine cabinet to find something to help me sleep/relieve the pain. I found a single ibuprofen tablet in the back of a drawer and took it and went back to sleep. All the while, I let my son nurse as much as he wanted in the hopes that it would be better by morning. I should also note that beginning a few days ago, my son's nursing has been very painful on my nipples. It's almost like when I first started nursing him and my nipples were raw till they got used to it.

The next morning, my left breast was definitely not as swollen but was still very tender to the touch and that top quarter was still very red. My husband put his hand up to touch it when I showed him and before he even made contact, he stopped and said 'Wow, that's warm!'. All day my breast was tender and inflamed, but I did not feel sick or achey anymore. That seemed to have been just overnight. At that point, I was just thinking it was mastitis again. But I did do a couple of google searches and when I read the symptoms of IBC, I started to get worried.

Now let me stop here and just say that I REALLY need to be on top of this, if it is AT ALL possible that it is IBC because I cannot get sick! Not just for the obvious reasons, of course no one wants to get cancer and/or die, but we have a 4 year old daughter who has cerebral palsy, is blind, is globally delayed and does not walk, talk, or crawl. She needs 24 hour care and I am under no illusions about her future needs; it is clear that she is going to need assistance for a long time to come. I am already stressed out enough about the fact that we had children so late so I (hopefully) only have about 30-40 years to be with her and help her but the prospect of maybe having a debilitating or deadly illness is not something that's an option for our family. I need to find out the quickest, most accurate way to confirm/dismiss these symptoms. If there is any chance that it may be IBC, I am willing to have a mastectomy as a pre-emptive precaution.

The red flags for me are as follows-
* As I understand it, mastitis occurs only when a milk duct gets plugged because it has been a longer than usual time between nursing sessions (this is why I got mastitis both times before, I was out of the house for an entire day and by the time I got home, my breasts were huge) But this was not the case this time, in fact I had nursed my son about 2 hours before I started to notice the left side swelling, so it would have been strange for mastitis to come on so quickly.
* If this was mastitis, it presented very differently than the other two times I got it. There was no actual lump (plugged duct) but instead there was just an inflamed red area and the whole breast was tender to the touch, including the nipple.
Also, there was the flu-like symptoms that I had not experienced before.
* The swelling came on so suddenly and the red area of the breast remained noticeable till yesterday (Monday). I cannot actually be objective about whether the redness is still there or not because I feel like I am still seeing it, but I'm not positive. DH said the same thing, he 'thinks' it's still slightly red in that area but it may just be because he saw it was so red on Sunday.

 So I guess my questions are -
1) Does IBC come on with flu-like symptoms like I experienced? And do they go away as quickly as mine did?

 2) Given that I dont have the orange peel skin or inverted nipple, what do I have to say to get the doctors to take this concern seriously?

3) What is the best form of test to ask for?

Last notes.
* The tenderness is gone now, even my nipples are not tender anymore.
* It's very possible that I was ovulating over the last few days and I had read that breast tenderness and sensitivity increases during that time, but I have never experienced it like that before.
* DH and I are hoping to try for one more baby so I have been drinking some fertility teas but not in large amounts, not on a daily basis yet and I had not taken any the day that his occurred.

I called my PCP and he can see me Thursday morning. By that time there may be no more visible symptoms so I'm going to have to make a very clear compelling case verbally to him to get him to take me seriously. Any suggestions??

My husband thinks I'm freaking out for nothing, and I hope I am, but in light our our situation, I have to be sure and I know that not many doctors are familiar with IBC so I wanted to get some opinions and suggestions to be prepared when I go to see my PCP.

Thanks so much for your help.
I truly appreciate any info you can offer.