Sciatica pain

I am 22 weeks with twin girls and I am having the worst sciatica pain I’ve ever had. It’s making it hard to even walk. I have a 1 year old son and I am constantly running after him but the passed couple of days I’m having trouble moving without shooting pain down my left leg. I had some pain with my son at the very end of pregnancy but this is 10x worse. I’ve tried heat which works for a while and stretching. Any helpful hints that actually helped with the pain?