What is wrong if i feel sick & nauseous, throw up, then have episodes of diarrhea even though i've only had chips/salsa the day before?

Many possibilities: These symptoms are so non-specific that there is no way in which to establish a diagnosis or even a guess without seeing you, obtaining a history and exam and perhaps some lab tests. See a doctor. Hope you are better soon.

Watch and wait. : This indeed could be many things, but if you are in good health, have no history of stomach or bowel disease, no other medical problems, and this has been present for less than 24 hours I would push fluids, and more fluids, eat simple foods, and not consult a physician unless you develop fever, develop blood in your stool or vomit, or get worse. Be careful you don't become dehydrated.