I feel your pain. Literally.

I have an old dancing injury but also being pregnant y sciatic pain is becoming pretty bad. I second the notion of a wheat bag, hot water bottle or those heat packs. I take one with me to work now. There are some good stretches you can do - yes it is painful but stretching out can help for a bit.
Try to not sit or stand in the one spot for too long get up move around then go back to sitting iykwim. Take some Herron or pandedol.


if all else fails you could see a chiropractor or something they can help also.