Sciatic nerve pain?

I have really bad pain in, I’m guessing, my hip joint area on the inside of my right side. It started back in October and it gradually has gotten worse. I literally can’t move my leg certain ways or it’ll hurt. I noticed yesterday that I can’t even sit crossed legged anymore. I’m not even sure what is causing it. Or how I can make it better. I try stretching but like I said, I can’t move my leg all that much. I noticed my lower back is hurting now too (right side) but I do have a UTI so I’m not sure if that’s what is causing the back pain. I notice also when I move my leg and feel the pain then it stretches down to my knee and that didn’t start until recently. Has anyone else experienced this or know what is causing it? I’m 26 weeks pregnant if that matters.