Red bump inside lip? Please help me!?!?!? Is this serious?!?!?

I have a red bump inside my lip, it's kinda at the top. I could pop it, but it hurts A LOT. It's not not razor burn. It itches a little bit, but it's not a yeast infection or anything. It's about the size of a pebble. And I am 100% it's not an STD i'm a 15 year old virgin. Could it be a cyst? Will it go away? I do not want to tell anyone about it unless it is serious. What do you think? I am worried! I have never had this before.