2nd miscarriage in a row! What's next?

I am currently going thru my 2nd miscarriage since December. 1st due to blighted ovum and the second stopped developing at 4.5 weeks. What should my next step be? I really don't know where to start. I'm thinking maybe 3rd time will be a charm? I have 1 perfectly healthy 5 year old and have been trying to conceive for a year now. Thanks for any help...