Honey- you need to see the doc. If he's had sex with ANYONE, you can't trust that he's clean. He could even be carrying an std and not know it. You don't have to tell your parents the specifics, tell them you think you have a uti or something if you need to. But be honest with the doctor, the doctor won't tell your parents. You need to get tested. Untreated std's can lead to much worse problems.

Use a condom, every time. You need to protect yourself.