Boyfriend felt something inside my vagina...Cyst?

My boyfriend was fingering me the other night and said that he felt something "hard, like a ball" in my vagina that he has never felt before. Is it a cyst???
 If so, what does that really mean? 
I am 17 and have never had penetrative sex, but my boyfriend fingers and performs oral on me. I do not take the pill or any form of birth control (assuming that is relevant info). 
Advice please!!!!!