After trying a lot of things what worked for me was cutting out negative food; usually gluten, lactose, fructose. Probiotics never did anything for me.
Since the advent of "gluten free" foods, specifically for coeliacs, the fact foods get advertised as "X free" leads a percentage of the population to believe that X is therefore bad and should be avoided for as-a-general-rule health reasons rather than health reasons limited to those who get complications as a result of X.