sex while pregnant

I haven't had sex in a long time, I'm 28 weeks. I am not a high risk pregnancy, just very big and dont really enjoy sex now.. i had sex tonight and had to stop because it started hurting. I'm very uncomfortable now and I feel swelled up. when I pee it burns like a mother you know what.... kinda feels like I'm cut down there? is this normal? or is something really wrong? I'm worried