If you are loosing your hair in clumps, it may not be just a cosmetic issue. According to a recent NY Times article, hair loss may be related to diseases such as Rheumatoid Arthritis, Diabetes, or Celiac disease. Please consult with your physician if you notice abnormal hair loss.
http://www.nytimes.com/2010/12/28/science/28conversation.html?ref=health