I know exactly what you are going through I have the EXACT same problem, the only thing is that Ive been trying to deal with this for the past 5 years to no avail. Ive tried many diets and MANY supplements, Ive lost friends and boyfriends over this. Im only 25 right now and this literally ruined my 20ies for me. Id like to chat, message me please so we can find a cure.
One of the best things Ive personally tried was a very strong probiotic called VSL #3. Only thing is that its expensive, but is very strong. I found it benefiting me better than any other, still though, the diet has to change completely to get rid of this "bug".
I think my main problem is that I cannot stay on a strict diet for more than a couple of weeks but I know from reading this forum, that it takes at least 6 months to repopulate the good bacteria in the gut.