I am sorry for your loss. You really need to speak to a doctor....if your current one will not address your concerns, I would find another one. It could be any number of things.
Good luck!
My mom, in the medical field for decades, once told me that pregnancy can really alter your body forvthe long haul. I'm thinking that even a short term pregnancy that ended the way that it did (sorry about that by the way) can screw up the hormonal balance for a period of time, the duration depending on the woman. After six months (beginning from the time of the last d&c) would firmly raise my concerns to the gyn and see if they are professional enough to refer you to a specialist or do whatever they can do to get you back on track. Or perhaps change your gyn. I'm also wondering if you have an iron deficiency which can contribute to issues of proper blood flow. I had a similar issue the one you are experiencing and I was advised that my iron levels where extremely low and that I must begin intake asap.
Good luck and I hope you feel better soon :)