I had diarrhoea for 6 months! And had tried various supplements which, whilst improving things a little, did nothing to cure the problem. Then, last month I tried S. Boulardii and had success in under 4 weeks! My regime is one S. Boulardii, one Every Day probiotic (with L.acidophilus Rosell-52 + Fructooligosaccharides) and one Veganzyme, three times a day with food.
My GP had thought I might have had campylobacter but it never showed up in any tests. I voluntarily stopped taking anything with sugar in it, carbs like potatoes which would turn to sugar in my system, and milk.