Debra gave you some good suggestions. Try those first. If those don't work, your doctor could try cortisone shots. Don't allow your doctor to give you any more than three within six months time. Cortisone did cure my mother of her PF, but it did not help me. I had to have EPF.
Another idea that has helped some people is a night splint. Your doctor may be able to prescribe you one to wear in your sleep.
Feel free to e-mail, and best of luck!