TMI: Body in shock?

Every time I eat about 20 minutes later I have diarrhea. I'm not sure if it's because I switched to the C shift at work so I'm only eating once maybe twice a day. I work 11pm-7am and I don't eat all night, I sleep from 8am-4pm and then get up and I either have some food or I'll wait a couple hours till dinner. I know it's not good for me but I can't eat on the night shift, or I'll be sick at work.