Hi, I'm an eighteen year old female. I'm 5'5" and around 130 lbs. I commonly get ingrown hairs under my arms. A few weeks ago, I found a small patch of skin that was darker than the rest under my right arm (I tend to sweat more under my right arm, and I haven't used deodorant recently). I assumed it was a normal ingrown hair and left it alone because for me, they usually go away on their own. However, over the past few days, the dark patch has swollen up into a lump slightly bigger than a pea, and is hard, round, and sore to the touch. I tried squeezing it a day ago and a lot of dark blood (and a tiny bit of pus) came out, but it didn't really help. It's still as big and tender as ever. I've never had something like this before. Is it really just an ingrown hair, or is it something else? Thanks for your help.