There is a rash on my armpit I’ve had for 5 days. I have not worn deodorant in 4 days and have not switched deodorant or washing powders in ages. I sincerely think it’s caused by friction or an overgrowth of something that’s irritated by sweat. I have been committed to working out for 6 days every week for 1 month now. I have recently started running for cardio and I think the friction from running has caused it. Suggestions for ways to help? What do you think it maybe?