Why do I get stomach cramps?

Ever since I returned from a three month trip to North Africa in January, I have been getting cramps in my stomach (they are high and sharp--not like period cramps that are deep). Sometimes it is after eating but other times they will just appear. About a month ago they appeared and the pain got so bad that I went to the hospital. They determined that it wasn't my appendix or my gall bladder. The doctor thought it might be an ovarian syst and sent me home. The pain subsided a few days later. However, it still comes back in a much midler form almost every day. I have had blood and urine tests and the doctors can't figure out what it is. Could I have contracted something while in Africa?