A sore/canker sore on tip of my tounge that wont go away!!?

ive been getting this sore on the tip of my tounge for like 7 years now.. it looks juss like a canker sore and it comes and goes all the time.. and NO it is not a STD because ive been getting it long before i was ever ually active or even kissed someone..does anybody know what it could be?!?