Hello. Since falling sick with vomiting and loose motions must have been a hard suffering - (fear, anxiety ) .It's stored in your emotional memory as a threat.  All the things around this suffering will be registered in your brain as being a threat. Now "eating food" is the thing which is wrongly associated with "falling sick" . Its wrong cause your brain is clearly OVERESTIMATING the threat to avoid falling sick. The overestimation leads to wrong probability testing since its emotionally laden. The thought process is irrational And hence whenever you eat , you feel afraid. Here you need to look back at your entire life and recall the number of times you have eaten all your life and the number of times you have fallen sick. And then you will realize that the real probability of you falling sick by eating is actually very small. You will  have to consciously revise alternative thought that " there is no significant evidence in your past that eating leads to getting sick. And hence I shouldnt entertain this thought"

Try this suggestion :- Whenever you are in the situation to eat decide whether, 1. You choose to , Or 2. You have to eat.