I too got dairy issues, yet I wasn't a big chocolate eater, mine was more milk and cheese. It would affect my sinuses, I'd get a constant runny nose like a cold, so much that it would embarrassingly drip and run catching me unawares at times, then an itchy face. It got diagnosed by a local homeopath after I'd been to many allergy clinics and traditional hospitals, all put me on anti-histamine drugs but they had their own problems. In the end I found Goats Milk, and Goat & Sheep's cheeses. Even steak could affect me but now after many years off cow products I'm clear so long as I don't have too much.

When I worked in countries that I couldn't get Goat or Sheep milk I'd have to have black tea or plain water on porridge. I found that even Soy milk was a problem. These days there are more alternatives like Almond milk and I'm generally ok.