Learning what my body doesn't like

I spent a good part of the weekend with various digestive complaints, including the really fun deep back pain I get sometimes that is not muscle or bone related and is so uncomfortable I just fold myself over hoping it will go away.

I think I am allergic to dairy, or at least higher-fat dairy. I had a couple sips of a latte with 2% milk and my stomach started feeling off right away. I had a matcha tea latte made with water, not milk, and I immediately couldn't breathe because I was in so much pain (I wonder if it is the whey protein, but I have whey protein in my shakes and I'm fine, so that's puzzling).

I'm going to cut out all dairy for a while and see how that helps.