I had it reeeeaooy bad for weeks. The pain woke me in my sleep constantly! I read that not only putting a pillow between your thighs/knees, but one also between knees and ankles as well helps. If they aren't thick enough either, you might still have pain, as it is recommended that you hip, knee, and ankle be level with each other. I tried and it has helped wonders for me, it just takes my snoogle and 2 pillows placed right to work lol
Tylenol, a warm bath (not hot) and a moist heat pad can help
Siatic pain, it actually stems from your lower back but you don't anyways feel it there. If the baby is sitting on just the right spot you will get it.