I've dealt with adult hormonal acne (moderate/severe) for the past 4 years on my face, and after a long Accutane cycle, I've had clear skin for almost 8 months.
However, it seemed that as soon as my acne on my face went away and the summer and hot weather began to roll around, my acne decided to show up in a new and interesting place...my armpits.
At first, I assumed I had some sort of rash from shaving. I will admit that I've never really thought about how sensitive the underarms are, and was notorious for a quick shave before the bar over the sink (DUMB). But, once I noticed the red bumps, I began being careful to moisturize and use a lighter deodorant. But, I work outside in the summer so I tend to sweat a lot, and that didn't help. Now, I have FULL BLOWN acne under both my armpits. And it's also around my armpits, so it is visible in any sleeveless shirt.
Not only is it awful to look at, but its so painful. I swear, a lot more painful than my acne on my face ever was.
Does anyone else have this problem and have any tips on how to get rid of it/treat it with over-the-counter products? I really would like to get rid of this on my own without making a bunch of trips to my dermatologist and spending all the money on prescriptions.
Thanks! 
To be honest I know this is going to sound gross but stop shaving under your arms for about a week. It could just be folliculitis. Wash with an antibacterial soap like dial and use a powder like zeabsorb because there's no way in knowing if it's bacterial or fungal unless you go to the dermatologist. So you could try treating it with both of those products if you don't want to go to the dermatologist.