I had the same thing happen to me; here's my story:I was diagnosed at 19 with Crohn's and/or possibly UC. I had huge tunneling mouth sores, diarrhea, blood in stool, mucous, infection, high fever, blacking out, you name it. It was found by signmoidoscopy in the rectal/anal area.
I took Azulfadine and Cortifoam and was in remission when I got married. I had a flare about 4 years into being married, I had to stop the Azulfadine because I became allergic. I went to the doctors on my husband's insurance, got the colonoscopies, endoscopies, barium enemas multiple times-everything looked fine except for "minor inflammation".
The doctors (3 of them) thought I was depressed, anorexic, a hypochondriac-I was so frustrated I burst into tears when everything came back normal. In the meantime I lost 20 pounds, hair was falling out, incredibly high white cell count, bleeding, couldn't keep food down or in-all of which they discounted.
My husband actually went looking for a new job to get better health insurance. I was so nervous going to see the new GI, who had been in practice 30+ years. He looked in my mouth, and examined my abdomen, he felt the ileum area under my left ribcage and said "Oh I can feel the Crohn's, right here." I had no idea it could move to another part of the colon. I started Pentasa the day I left his office.
He followed up with a colonoscopy and when it came back with minor inflammation he said Crohn's often hides in the deeper tissue of the bowel and is not always visible with a colonscopy. Also, it's trickier to diagnose when it's in the ileum area. Six years later I needed an abdominal hysterectomy, and the surgeon inspected my bowel with my GI since "they had me open" they said-and lo and behold, the Crohn's damage was all over the OUTSIDE of the bowel! It blew my mind.
Looking back I should have taken my medical records from the first diagnosis and insist the new doctor accept I already HAD a diagnosis. Any decent GI knows that Crohn's is extremely difficult to diagnose unless you are at a critical stage, and even then it's tough. It totally pi$$es me off when doctors treat you like it's YOUR job to match the symptoms the book says you should have. Any doctor does that throws up a red flag in my book.