Overnight, 6 armpit cysts appear

I went away for the holiday weekend and did some solid partying, sleeping poorly on shabby couches for three straight nights. Aside from feeling generally depleted when I awoke this morning, I discovered 6 lumps under my armpits. They are hard, located under the skin, somewhat painful to the touch, and range in diameter from about 2-4mm. I'm 24 and otherwise healthy; I do not shave my armpits and I use Mitchum deodorant, which has ben the case for a couple of years.

Based on the reading of this forum it sounds like I have sebaceous cysts. Do these go away without antibiotics? Why did so many appear simultaneously? How can I prevent this from happening again?