I just had the same thing. Mine was red and started like a pimple then grew to the size of a grape or the like within a few days. It got painfull too. Went to the dock and it was a oil. Doc put me on antibiotics....the alt to cutting it open and draining it. But now after about 2 weeks the boil has shrunk to almost nothing...kike the doc said would happen but now I have some kind of cord or string-like thing around the same spot......scarring the S outta me!! It feels and looks like a tendon....but I'm pretty sure there aren't tendons in the armpit. If all you have is a boil you'll be ok. Just go see the deck and they'll either lance and drain it or put you on antibiotics and let it take its course. Hopefully you don't get the same sord-like thing that I have......has me pretty scared wondering what the heak it could be. I def wouldn't try to pop it yourself.....you can goto youtube and see some nasty vids of people doing that. Id rather leave it up to the professionals. Hope this maybe helped a bit.
