Bloody Diarrhea

[Runner32]

A couple of years ago, I was training for a marathon.  I started with 3 mile runs and worked up to 12 mile runs over a 6 month period.  Suddenly, I began getting severe abdominal cramping during my run and would have bloody diarrhea.  A few days following the bleeding, I would be constipated and my stomach would be bloated.  It did not occur every time I ran and the food I ate did not seem to have any impact.  My doctor had me stop running after the most severe attack and schedule me for a colonoscopie three weeks later.  The colonoscopie revealed no abnormalities and my doctor was not able to determine the cause of the pain or bleeding.  Last week, my Dad was admitted to the hospital with diverticulitis.  In talking to him, I discovered that he too had experienced periods of bleeding and a colonscopie that did not reveal any problems.  Is it at all possible that I have diverticulitis?  I was 30 years old at the time of my training and was in good shape.  Is diverticulitis heireditary?  Are there treatment options beside not running?