I’ve had diarrhea (non-bloody) for years. My PCP says I might have colitis. About what percentage of people with colitis have non-bloody diarrhea?

Big percentage. not every bloody diarrhea is colitis, and the lack of blood does not exclude colitis.chronic diarrhea deserved a good GI work up could be a simple irritable vowels syndrome , food allergy, sprue like syndrome, or colitis. See GI specialist.