I had an attack of colitis in early May that was diagnosed via abdominal CT as C-diff colitis. I have had symptoms similar to Irritable Bowel Syndrome for 3-4 years, and nothing seemed to help, including probiotics twice a day for 2-3 years. After being treated for the C-diff colitis, I feel like a different person. In reading I found that C-diff can be a latent infection that lasts for years, mimicking IBS. Probiotics are great, but in some cases may not help. (FYI - I'm microbiologist).