Painful sex?

This may be a stupid question but is it normal for having sex to hurt? I’ve been consistently sexually active for about 3 years and after my first time I’ve rarely felt even a little bit of pain. I got into a new relationship about a year ago and at first the sex was GREAT. I mean amazing. But as times gone on it started to get painful to do it. I know it’s less foreplay than before but I’ve had sex with almost none and it never was painful. Today we tried to get it on but it just really hurt, it was awful. I still kind of feel pain down there. I don’t know what’s going on? I’m 17 and my mom would ring my neck if she knew I even thought about sex, so the lady doctor is out of the question. Does anyone have any advice?