Nov 08, · Very intense burning pain in my right breast that radiated under the armpit, travelled down my arm to the elbow. There was so much anxiety and panic and I feared the worst, as at some point I was feeling like my whole body was burning, yet I had no fever, the breast was not red and may be only slightly swollen. Oct 12, · Infection of the breast tissue especially by staphylococcus aureus bacteria or mastitis can cause pain in breast as well as under your armpits because a small part of the breast tissue extends into the armpit area. Common symptoms will be lump, pain, itching, discharge, swelling, redness, etc. of breast and n1pple as well as enlarged lymph nodes.