I got a Swisse Ball and sit on it and do Pelvic floor tilts, rock my hips from side to side, sit on and do circles clockwise and anticlockwise (this was from my pregnancy Pilates class). I also say a physiotherapist and she said to get my husband to dig his elbow into side of the buttock. It hurts lots but the muscle is very deep and hard to get to apparently. These things all helped me as I could barely walk some days around the 28 to 32 week mark!

Now I am much better but the pain returns at night. My Physio place a pillow between your legs or if its really painful use a swisse ball. I know hilarious when you are in bed with a giant ball! But make sure your knee is higher than your hip in bed (this is for sleeping on your side)

I love my Swisse Ball!
Hope this helps!