What Causes Bump In The Labia?

Hi, on the right side of my labia i use to get one small bump it itched sometimes but then it would go down/away, ive been checked numerous times and ive had an sti but treated for it - this came after got checked again and they didnt say it was herpes of warts or anything, now i have more then one bump but they are small and only on the right side of my labia, when i itch them they get a bit irritated and the ight side swells up a bit. can you tell me what it may be?