You could start charting (taking your waking temperature each morning), to see if that could possibly tell your doctor anything. If nothing else, you'll for sure be able to tell if you're ovulating or not. It probably won't give any clues as to why, if you aren't, but it's a start, perhaps. A good online resource to learn to chart is fertilityfriend.com I personally used the book "Taking Charge of Your Fertility." I personally wouldn't buy it if I were in your shoes, but maybe your local library has a copy you could check out.
Status: Remission since May 2009!
Symptoms began in November 2008, ~4 weeks after giving birth to my son
Diagnosed with pancolitis on 1/30/09
Meds: Apriso (4 0.375g pills ONCE!! daily), mesalamine enema twice weekly, Natural Factors Ultimate probiotic 12/12 Formula, multivitamin. Used prednisone (starting dose 40 mg) to get into remission.