I am also experiencing secondary infertility. I had my son who will be 3 next month and have been trying since he turned 1. We had no problem conceiving him. My husband and I have had every test in the book. 2 HSGs, laproscopic surgery, blood tests, ultrasounds. We are unexplained as everything came back fine. I had 2 failied IUI's, and did IVF in may and got pregnant but just miscarried at almost 8 weeks. The dr's have no answers for me except that I'm 38 although my fertility dr doesn't seem to think that is too old. I guess because he has lots of women in their 40's. anyway - I don't know why this is happening but it's VERY frustrating and such an emotional rollercoaster. Good luck and let me know if you have any questions or need advice. I've been through everything trying to get pregnant again. I also have been told by everyone I meet including my fertility dr to just relax. it drives me crazy! good luck!
Welcome and best of luck :) Was HSG the first step in figuring out what may be wrong or did you have other tests done too?