I'm experiencing a stinging sensation in and around my inner-upper arm near my right arm-pit. Pain started during a long run when my arm sleeve seemed to have chaffed this area. I still have this pain after 2 weeks whenever I get to the point of sweating while running. There's no redness, no bumps, no signs of chaffing, no pain when I rinse or shower this area like a chaffing would cause. I've used Destin alone and with bacitracin and hydrocortisone, but no change to stinging pain. This pain seems to appear whenever I reach to the ground or change my arm swing while running and sweating.