For heat therapy, instead of a heating pad you could try a rice bag. It’s softer, more flexible and safer. If you can’t find one to buy or sew one yourself, a sock half filled with raw rice and tied at the top will work. Microwave it for about a minute and a half, check the temperature before you use it. Along with the heat, I think I remember finding some relief lying on my side with my belly supported by a pillow and of course one between my knees. Perhaps MagRags will be in with some advice.