Why do I get diarrhea in the morning only after I eat?

Up until two years ago, I had been able to eat breakfast during the mornings before school. Two years ago I moved and on the 4th day at my new school, which I hated, I nearly had to go home because of diarrhea. I skipped the next day because I thought i was sick, but nothing was wrong. The same thing would happen frequently until i realized it was only when i ate breakfast. The foods i ate helped me partially predict how bad it would be. Things like pop-tarts would only occasionally affect me while meats and eggs would range from bothersome gas to diarrhea. I try to keep Imodium around, but it's not always possible. This ONLY happens between 9 AM - Noon at the latest and only when i eat food before school; not during the summer and not on weekends. Also, i began to sweat EXCESSIVELY, mainly armpits, throughout the day (whether i ate something or not). This started around the same time as the diarrhea from eating, but i doubt is related. I have since then moved back to my old town, which i love, having only spending one year at the new school, but the problems still persist. Because i don't eat in the mornings i am exhausted all day, but it seems better than diarrhea. Any tips on what to do to make diarrhea better when i do have it? Aside from pills that is. it would be handy to know of a household method i could use. And if there isn't a remedy, any ideas on prevention?