Strange bump, like a pimple yet hurts?

So, about a week ago I noticed a strange bump on the outside of my vaginal lip area (on the right, panty line) [I don't wear too tight clothing and only cotton panties], I thought it was just a pimple and decided to ignore it. Today it began hurting when I moved, I tried to pop it and nothing happened, I tried to see if there were ingrown hairs but was unable to tell. It is now even more irritated and hurts when I walk or sit a certain way. Any suggestions would be greatly appreciated. Thank you. Oh, and I am sixteen years of age.