Pain during sex

During sex I always feel pain or a weird kind of pressure. I use to be able to tolerate it but now it’s getting really uncomfortable. The only position I don’t feel this pain is when I’m on top. I’m not really sure what the pressure is, like could it be that he’s hitting my cervix or is it something else. I’ve also been thinking that maybe it’s because I can never fully relax but I’m not too sure if that could even be a reason.