Messy Issue: Diarrhea

I'm about 2 years post kidney transplant. I've determined that if I eat oily foods I'm more apt to get diarrhea. I've tried to steer clear of those kinds of foods most of the time. Lately, I've noticed that when I drink a coffee latte from a certain stand (a local store, not national) I get diarrhea about 2.5 hours afterward. Yesterday, I had an onsite meeting so I stopped for coffee prior to it. A few hows afterward I got diarrhea, I even had to take a second shower, at least I had made it home before it happened. Working from home has it's benefits. I've made coffee lattes at home and haven't had that issue. Coffee seems to go through me faster than food is normally processed, Is it around 72 hours?

Has anyone else had issues with getting diarrhea after getting coffee, specifically a latte? Or other foods/drinks?