Are you a smoker? This is from PubMed, what I consider to be one of the most trusted sources of medical studies. (Click on the links below.)
http://www.ncbi.nlm.nih.gov/pubmed/12673073
"Association between smoking and hair loss: another opportunity for health education against smoking?...
Besides being the single most preventable cause of significant morbidity and an important cause of death in the general population, tobacco smoking has been associated with adverse effects on the skin.... indicated a significant relationship between smoking and baldness."
Another one,
http://www.nytimes.com/2008/05/20/health/20real.html The Claim: Smoking Can Cause the Loss of Hair
In addition, smoking is one of the most critical factors in relapsing crohn's.
Hair loss could be from Lupus as well.
Good luck, I hope you get it figured out.
Jan