Again!!! I don't know how long I can do this!

It's just been confirmed today. I have had my 3rd loss in 6 months. Again at 6+2. Why.??? I have 3 healthy children. All with no complications and my last child being born March 2014. Cause this is my 3rd loss in a row I'm now being referred to a specialist to find out why. My doc thinks it's my progesterone. Does anyone have progesterone issues? What are ways to fix it? I'm just so over feeling this pain.