(( VaginaPagina ))

don't be worried about this. everyone has had a time when they thought they felt something funny in their vagina, but there's really not much it could be that is dangerous, even if it is something other than just a normal body part. i promise you, it is not cancer. about the worst thing i can think of is that it could be some sort of cyst, and these cysts are generally benign and not a problem (but a cyst doesn't fit with your description of a ridge and hard base, that's just the usual kind of 'funny thing you feel in your vagina that isn't your cervix').