Red lump on inside of inner lips of ?

I have recently discovered a red lump ( a small round lump the size of a pebble). I am 17 and a virgin so I don't think it can be an std/sti. It doesn't hurt or itch and it doesn't hurt when I pee. It is just there and I haven't a clue what it is? I recently had a yeast infection if that is any help? I don't think it is an ingrown hair as I don't shave their. I don't want to talk to my parents if it isn't something serious. My boyfriend and I are planning on going further tomorrow so obviously if it is something that could be infectious to him I want to avoid that. Any help or advice would be nice :)