A typical "I have a rash, how worried should I be?" post..

Hi there. I know these kinds of posts are really common and that no one can confirm anything, but I don't know where else to turn. No one in my life is taking me seriously and I figured that people with direct knowledge and experience in the subject would be the best for listening, understanding my fears, and providing feedback. I'm sorry if this gets a long, I sometimes talk a lot when I'm worried!

I have no history of breast cancer in my family that I am aware of and I am just barely 18 years old. I know that both of these things drastically reduce my likeliness of having cancer, but I have concerning symptoms and no health insurance -- which is why for the last 2+ months my mother hasn't taken me to the doctor despite my requests (smart, right? She's a nurse but has a tendency to downplay potentially serious medical matters...). Since I've just turned 18 I'm going to be applying for healthcare soon so hopefully I will be in with a doctor in the very near future. Though I have to say that I honestly don't know if I'll be able to entirely trust my doctor, a technical pediatrician, to determine for certain whether or not a rash is breast cancer. Especially with my general history as a bit of a worry wart.

I'm working myself into such a panic over this that I'm considering taking a trip to the emergency room. In the mean time, here I am.

So now that that's out of the way, the problem itself: one night in late June I noticed what appeared to be a tiny bugbite on my left breast on the edge of my areola. It itched only slightly and I thought nothing of it. As the days went on the itching increased and in time more bugbite looking marks have appeared on the skin surrounding the area. I've been putting hydrocortisone on the area pretty regularly and it does seem to help a bit, if only temporarily. It will cease the itching and will temporarily fade the 'bites' to a nearly unnoticeable appearance. If I'm lucky it will go for a few days being nearly unnoticeable and I'll think it's finally gone, but then it will become just as prominant and itchy again. 

When I started Googling to figure out what could be wrong, cancer was the last thing on my mind but now it's all I can think about. I am a bit of a hypochondriac which doesn't help, but I'm trying to keep that in mind.

I have naturally small breasts (even though I've never really been a small person...) and one has always been the littlest bit larger than the other (the one in question), but it doesn't appear to be any larger than normal. It currently feels a little weighted, but I am also on my cycle (which I have a whole host of issues with that, not sure if it's relevant or not. But this is the first cycle I've had in months so I'm not sure if it's just taking a harder toll on my body than usual). The breast doesn't really hurt, but the last two nights it has felt kind of cold and clammy INTERNALLY, but not to the touch. Which is strange to me because you would think that if anything, it would feel warm. The skin itself, aside from where the rash is, doesn't look or feel abnormal that I can tell. The nipple on that breast seems a little less sensitive than the other one is, but I'm not sure if this is recent or not though I can say I haven't really noticed it before. I don't seem to have pain in the breast though last night I did feel some discomfort in the upper rib area. A week or two ago my left arm hurt horribly, but this isn't all that new. It hasn't happened in a while but it's happened before. Of course when it did in the past I went to the doctor all worried  thatI had a heart problem, underwent an EKG and they sent me home saying I was fine and made a point to tell me that 'didn't sound like cancer' (that was a year or two ago).

The fact that the rash temporarily lightens up makes me feel a little better, but the fact it's still here and has spread  from one bump to several localized bumps over the last few months makes me uneasy. I would think though (and I could be wrong) that if it were REALLY serious, the symptoms would be a lot worse two-three months in, but I have no idea.

Should I be worrying as much as I am? I know no one can diagnose me except a doctor, and even then there are a lot of misdiagnoses...
I'm sorry if I just sound like a paranoid little girl getting worked up over nothing, that really isn't my intention. 
Thanks in advance.