Go to the doc. Seriously. I had one for ages, while I was pregnant, that we left alone to see if it would go away. It didn't, then got infected like two days after DD was born. It was right on the middle of the back of my neck just below my hairline - I couldn't comfortably lay down to sleep! Though I just had a newborn! I got it lanced, took the antibiotics, and life was wonderful in like three days. (Well, the boil bit, not the high-needs newborn...)
Re: So this is kind of gross
Also, OP. Go to the friggin doctor. You have no idea what it is. Golf ball sized things appearing on your body is not ok.
::runs to google::