I, too, developed lactose intolerance in my late teens/early 20s.
I have it pretty bad, especially since I absolutely love dairy. This was like a cruel trick from God, and I ask Him often what I did to deserve it.

Like Nessa, I can have a little bit of ice cream (like a Snickers Ice Cream Bar or one scoop of Breyers Oreo Cookie) once in a blue moon and I'll be ok.
Only a few cheeses bother me, thank God. After all, a life without cheese is a life that aint worth living.

[useless trivia] Did you know that in 2000, it was reported that 78% of Black Americans are lactose intolerant? [/useless trivia]