Why do I have diarrhea?

I'm not even sure if it's diarrhea. I feel totally normal despite, every couple of hours I have to hold it fast before I get to the toilet. This has been almost 4 days. I've lost my appetite knowing that it's all going to come out in less than an hour. Could this be a parasite? It started after I had made some vegetable stew. How do I make it stop!