A few years ago my best friend was complaining of stomach aches also. He went to see a few doctors, they either didn't know what was causing it, or said it was probably Crohns disease.
They started treating him for Crohns for about a year, but it wasnt working. He had to drop out of school (Berkley) and fly back to DC to get treatment. A few months later they told him it wasnt Crohns disease after all, but cancer.
He had tumors all over is intestines and omentum (membrane that surrounds your intestines). It was inoperable and he died 6 months later.
Make sure they are sure its Crohns.