Why do I get diarrhea when I eat out?

Question

I don't get it when I eat fast food or eat at home but almost every time I go to a restaurant, it hits me.

Answer 1

Possibly bad food.  

Answer 2

It could be nerves, IBS (Irritable Bowel Syndrome) or anxiety. Do you suffer from nervousness or some sort of anxiety? If this happens every time you eat out and at different restaurants, it is safe to bet you have an anxiety disorder.  Do open spaces, strangers, new environments, etc. make you feel uneasy? Your doctor can help. Go and see him. Good luck.