Pain after miscarriage

Hi everyone, I writing to see if I can find someone who had experience pain after miscarriage.  I had a miscarriage when I was 12 weeks on March 11, 2015. I bled for 2 weeks but After that I continue to have lower mild pain. My doctor ordered a sonogram and it showed that I had some stuff left from the miscarriage . So he rushed and have me done a D&E on May 1. I was ok for one month, no pain. But after that I continue to have pain. I never ever have cramps before that,  but now it's like experiencing another miscarriage. The pain is awful. I went to see my doctor again and He can't figure out why I'm still having pain. Someone help me please. We be trying since June but I can't get pregnant 😢.