Pain in cancer breast...3 years since Diep Flap

I was diagnosed in October, 2011. Had a BMX in December, chemo, then a Diep Flap in July 2012. With revisions and everything, I was done in December 2012. Through the years, I have had a few necrosis, made them biopsy one, had an MRI and all has been good. In the last month, I have started to get increased pain on my cancer side. I can't really tell if there are lumps or anything, nor do I even know if I am supposed to feel them! I see my MO on Tuesday, but for the first time, I have a bad feeling and am very scared! With all the info on the internet, I cannot find anything useful about recurrence, how and where! The pain feels almost like a muscle pull, but at times feels tight. It started under the breast and is now moving up the outside of the breast. It is also under my arm and is much more tender with touch. My friends do not seem to understand and tell me that I am fine...but I am more scared now than I was when I was first diagnosed!

Help! Is this how a recurrence feels? Could it have moved to my lungs? I had such a great support system around me the first go round and never really turned to the community, but now...Do I insist on an US or MRI? Can they tell by a clinical exam? Does lab work show anything abnormal?

I know I will find out more on Tuesday, but I am going crazy! I just really need to hear other peoples experiences!