I quit the junk about 6 months ago (still asking users for their remedies though because I'm curious and sometimes smell bullshit with their stories) but have felt progress after around a week of dieting. As I already said: Less gluten, lactose, and fructose. You have to be really careful. So mainly eat rice, rice cakes, potatoes (soak them in water a day before eating them to get rid of most of the fructose), chicken (boiled or grilled, doesn't matter, but without seasoning or spices, just salt), and vegetables (porcini, peas, few carrots, spinach, avocado). No juice and soda. No alcohol or other drugs of course.
Of course you can also eat fish or eggs but if you think that TMAU is your problem, don't.
Follow this diet for a few weeks (4-?) and make a diary if it helps you with keeping up.