What Could Tender Breast & Armpit With High Temperature Suggest?

Hi.I have tender breasts, and armpits and my body temperature fluctuates for no reason which makes me feel fluey. Please would you let me know what you might think it is? I am 30years old, 167cm in height and approx. 11stone in weight. I am on thyroxin for an underactive thyroid. 200mg per day.