So painful to walk through contractions

I am not having consistent contractions but every time I have one tonight, I physically cannot walk. It’s excruciating to even try to take a step. I have to wait till it passes before I can attempt to walk. I can still talk through it and as long as I’m standing still I’m okay. I can’t straighten my back out completely during one either. It’s hard to pee right now because baby is so low. I don’t have a UTI. The only thing I can compare the pain to is a strong gas pain in my lower stomach/vagina. I don’t know what’s going on. I’m 36weeks pregnant. Anyone else experience this? Also experiencing pain in my lower back and I’m nauseous. Not ligament pain because it only happens during a contraction.