It might be one of your lymph nodes. We have them in our armpits and if we're dealing with any infection or inflammation, hormone changes, they'll get tender sometimes. Do you feel any lumps if you press into your armpit?
Our periods will cause lots of strange things to happen. Oh the joys! Might want to run this past your doctor.
I can do anything through Jesus Christ who strengthens me. I have learned in whatever state I am in,to be content. Phillipians 4:11-13
34 years old. Diagnosed with Lupus in 2000. Fibromyalgia, Anti-phospholipid syndrome(APS)(stroke, 2002), Sjogren's, Raynaud's, Libman Sach's Endocarditis, vasculitis, sacroiliitis, arthritis (neck), anxiety. Prednisone, Imuran, Coumadin, Clobazam, Amitriptyline, Didrocal, Cozaar, Zoloft, Neurontin, calcium, multi-vitamin, vitamin D, Magnesium, vitamin B6, Acidophilus