Interesting, I have some kind weird dairy intolerance that isn't just lactose intolerance (I have that too), but some kind of sensitivity. When I cut out all dairy my weight jumped 25% in 6 months, and I was no longer underweight or feeling chronically sick. I had cut out lactose heavy dairy years earlier (soft cheeses, milks), but still would have hard cheeses and lactose-free products.

I have no idea what is causing this and my doctors have just shrugged. I have no idea where to even start with this.