I love coffee, and for the most part, it doesn't give me any issues. However, sometimes, if I'm using half and half or drinking a latte, I'll develop extreme stomach pain and/or diarrhea. I've never had this problem using heavy cream in my coffee (yet - just switched a couple months ago), and I've never had this problem drinking milk products alone either. I typically don't react to lactose.
So, do you think the coffee is exacerbating a mild lactose intolerance that I otherwise don't notice (if so, how?), or do you think there's something about the combination of the two that's causing the problem?