Pain & Sex

J`sMommy
23 weeks and 5 days. Haven't had sex for a week. Then I get to it. He's on top. The last two minutes my back starts to hurt and my stomach feels uncomfortable . I just push through. So when it's bed time. My stomach is uncomfortable. I wake to pee, come lay back down. & It's just really uncomfortable. No cramping or bleeding. I don't know what's wrong. Is this normal? Has this happened to any of you? Or something similar ?