Girls, tell me — since about week 20 I've apparently pinched my sciati…

Girls, tell me — since about week 20 I've apparently pinched my sciatic nerve. I wake up at night screaming from pain in my lower back on the left side, in my leg and under my belly, all on the left. I bought an applicator, it sometimes helps, but it can start at any moment, it even happened to me out on the street... How did you cope? The doctor said it will go away after delivery. Do I really have to endure it for that long?