I was going to the doctor for severe digestive issues from early infancy. I was put on medication that had to be given to me mixed in whatever I would take, several tablespoons of foul liquid a day. The doctor told my mother to mix it into whatever sweet drink I would take, and that it would ruin my teeth but they'd have to deal with that later. I wasn't thriving otherwise, there really wasn't an option. Sure enough, some of my baby teeth were pulled and the rest were capped until they fell out. It was painful and embarrassing and it cost about as much as a new car did at the time.
Fortunately as an older child my symptoms improved somewhat, but I wasn't an especially healthy kid and I continued to have a lot of digestive trouble. I also gained skin, respiratory and sinus trouble, and went on more medications. Nobody connected them or pointed out that there might be some underlying cause. Things happen, you know?
Anyhow, that's how things went until I grew up and had my kid. As an infant he was diagnosed with a dairy allergy because of some reflux and it hit me: That's what's wrong with me too! So I cut the dairy out of my diet (I had to anyhow because I was nursing the kid, and he was allergic,) and there had been a lot because that's what I was being told to increase while I was pregnant/lactating.
And guess what? I didn't need my inhaler anymore. My digestion improved. My skin improved. My anemia went away. Soon enough I wasn't on ANY medication, for the first time since my first week of life.
Of the dozens of professionals who had treated me, none had ever suggested that my digestion had something to do with what I was eating.