Someone help??

Sara • 1st baby. 💎 scared, but excited!!!😍
I keep having this awful pain somewhere in my hip. I can mostly feel it kinda on my butt cheek... but I'll be walking and then the pain kicks in and I almost fall. I'm 31 weeks pregnant and I can't even sit down for too long because the pain comes back and feels like it's paralyzing me... anyone else felt this or know what it is.? Idk if I'm explaining it well or not...