It hurt when I had sex

Last year I got into a new relationship with a guy I really like. About three month in I started having horrible pains in my vagina when he would try to insert his penis. It would hurt so bad that sometimes I would push him away and just cry. But when he did get it in the pain would eventually stop after a few minutes. It lasted for about 6 months and eventually went away. I was tested for STI's and didnt have any and nobody could really tell me what was going on.

Has anybody experienced this before? Is it something that's going to happen again?