I have a really gross question...sorry...,?

Lately, I have been having stomach upset, (nausea, cramping, bloating, my heart racing ) when I would consume dairy. I looked up all the things on lactose intolerance and figured that would be it. So i bought some lactaid. Today I ate about 2 oz of hard reduced fat cheddar cheese with the lactaid pill. Within 2 hours I was vomitting. Just once. The disgusting thing is that I vomitted the cheese (and some green beans, which I ate for lunch at 1200.) This all happened around nine at night. I know this is TMI and gross, but any theories? Thanks. I am calling an allergist on monday.