It comes down to what I always say: you have to be your own best doctor, and that's true for diet, supplements, and meds too.
The best way to start is through a food journal. Write things down and the effects it has on you.
Yes, we are all individual, and unfortunately what works for some may not work for others.
Itsalwayssomething, the Paleo diet - eating grass-fed animal products with plenty of veggies, salads,healthy fats, and nuts, and low fructose fruits, with the exclusion of dairy and all grains - has been evolutionary for me.
I've finally gotten to it after trying different diets which didn't help, and finally piecing different pieces of the puzzle together, and then in trying to understand the different pieces of the puzzle and the big "why" I needed the medical research to back it up -- all this finally got me to grass-fed animal products. I hope it works for you too.
Let me know if there's anyway I can help.