I have lactose intolerance, and my symptoms are a little different. The symptoms usually start within an hour or so of eating the food, not the next day, and I get bloating, cramps, gas and sometimes diarrhea, depending on how much I ate without one of my supplements.

Do other dairy things ever give you trouble? If not, I wouldn't say you have lactose intolerance. Maybe the greasy food at the diner just made you feel a little weird, many people have that problem.