breastfeeding and getting checked for breast cancer

Were at 2 yrs my son would only take my right side started refusing left boob early on never engorged leakin anything on that side he still feed from the right i have a vein rash thats formed over the last few months and sometimes I get pain and am gettin a mamagram and ultrasound done nxt week Im 33 but cracer runs on both sides of my family tryin not to freak out what else could cause this? It almost looks

vein bruise rash ob was concerned enough to put in order for me to get the mamagramand ultrasound milk still comes out but i have always had way more on my right