My symptoms of gluten intolerance were very, very crampy bowels and frequent stools. What I always called "IBS". Within two days of getting off gluten that resolved. I've noticed since then that when I get glutened I also get fatigue and brain fog.

Traditional doctors can't detect gluten intolerance until you're extremely ill at the point you can't absorb nutrients from your food properly. Some people never get to that stage. Some have no intestinal problems at all, but end up with brain lesions and neurological problems like gait problems or speech disorders. Its affects people so differently than what most doctor's were trained to recognize as gluten intolerance that they're untrained to really recognize it.

enterolab.com has a good gluten test.