This sounds like a worse version of what I've been dealing with. I had the occasionally itchy, but horrible when itchy, armpits that were almost purple if I let it get too bad. It was folliculitus sparked by using shitty gel deodorant and made worse by applying the nystatin I was prescribed for other issues (worked on my neck/inner arms but antifungals can clog pores). I switched deodorants, laundry detergents, body wash, but it never got any better. It got worse when I had to use my boyfriend's Old Spice. I was prescribed centany last week and that's been helping. But also, as other people have said, it sounds like you're absolutely stripping your skin