I have a lot of sciatic pain due to arthritis,if the heat isn't helping,try icing it down and the pillows between the legs is a good idea,i do that every night now,prop your self up with some pillows,if you like to roll around at night or try them under your knees,I think that is what it wanted if you sleep on your back
a soak in a tub of hot water may help,if you can get up and down
and some serious pain meds help the most and look on the bright side,it is just pinched,so it should go away and not be a permanent thing
oh and what ever you did to pinch it,don't do it again lol