Sciatica pain

I literally get sciatica pain EVERY SINGLE NIGHT on the left side of my body. WTF!!!! Physical therapy not until July 17th my OBGYN scheduled for me. I sleep with a pillow between my legs, I take Tylenol, I do stretches but nothing works until SOMETIMES the next morning. If I got a good enough sleep. What even causes this??? 23w3d been getting it since 15weeks