What is causing stabbing pain below tailbone after an orgasm?

Hello everyone. After consulting with 3 different gynecologists and having them all look at me like I'm crazy, I'm hoping I can find at least someone who knows what I mean. I've always had issues with my period, and it's always been painful, but within the last 3 or so years it has gotten way worse and I started getting pain during my period when I would defecate, that I can only explain as this extremely sharp pain that's like below my tailbone, and wraps around to my pelvis. It feels like pressure until I cough, sneeze, sit, or exert myself in any way while I'm having that pain, then I feel the stabbing pain. Within the last year though, I haven't suffered with pain with defecation during my period, but instead I'll get that stabbing pain after an orgasm, whether it's with my boyfriend or when I'm masturbating. It happens all the time now and not just during my period. I never know when it will happen, it's basically just a gamble. If I start to get the pain 99% of the time we have to stop because it hurts too bad. I'm lucky to have a guy who is very understanding and caring, so it doesn't bother him when I can't finish, but he is very concerned something is seriously wrong with me. But no one seems to know what I'm talking about and I feel crazy. I've just kind of stopped trying to find a new gynecologist after the last one basically called me a liar because I was 21 at the time and still a virgin. But now that I'm in a relationship and having intercourse, I need to address this problem because it's happening more and more often, and my boyfriend is really worried and wants me to get checked out. I'm going to keep looking for a new gynecologist, but I just want to see if anyone else has experienced this. Also just a bit more info about me, I'm 22, my boyfriend and I use protection but we're also the first people we've ever been with. Still want to be safe though. Thank you in advance for any help you can give me, and sorry for the TMI!