4 weeks ago, i got back from a one week vacation from my friend's house out on the lake, when i got home, i started noticing an itchiness in my right armpit. It started to look like a little tiny patch of a rash of some sort, as a week went by and it didn't go away, then i started getting bumps or "boils" that started appearing and hurting, a few zits here and there. But i didn't think nothing of it, so 2 weeks later, i started applying Tinactin antibacterial cream thinking it might had been some kind of bacteria of some sort. Then the "rash" started appearing pink and seemed like it was disappearing, but it still itched, The third week, i started getting more bumps underneath my armpit. During last week, 3 new bumps showed up, 2 extremely close to one another and they grew quite large, now it feels like i have a big knot in the middle of my armpit and its kinda painful to raise my arm.
I've never shaven my armpits.
i've used the same deodorant for the past year, no new detergent is being used.
i DO wear tighter t-shirts and my brother is 13 and has acne problems and likes using my towel to wipe his face with. could that be a cause also?
my friends suggested i just use cortisone.
but i want to be cautious and not use something that i'm not sure what it is and cause the rash to get worse.
I need help, what is this?
and how can i make it better?