Both of my armpits are sore and sort of feel like shaving rash but heaps of small tiny bumps under each armpit that hurt.. should I be concerned? Does anyone have any idea what it could be?? Thanks :)

Have you used a different deodorant recently? Could be possible heat rash. Do cool compresses help relieve the discomfort at all? Then let air dry and wear loose tops to allow better air circulation. Avoid deodorant until it clears up or have your doctor check to determine the cause if it continues.