did you have it when u were younger or born with it? what causes it say sensitive to some foods and how do you know?

My dctor says I dont have any but mine is more based on anxiety adn fears of having things cause sensitivies but I know their is some people out their with real sensitivies like you here and want to know your experience. I know mine is alot of my behaviour as I have alot of fears. never had probs in the past.

how do we test properly for sensitivity? Im scared to get replacements.