Sleeping Hip Pain

I am 18 weeks pregnant and not really showing yet. I am usually a stomach sleeper, but haven't been able to do that for a couple weeks now due to the pressure. However, when I sleep on my sides, my hips hurt quite a bit in the morning. Sometimes it's just like a numbness, sometimes actual pain. I have tried pillows between my knees and other positions I can think of. 
Does anyone have any ideas on what to do or how to help?