Is The Key Lactose-Free?

I love ice cream, and will definitely need it in the summer ahead.  But sometimes ... well, to be uncouth, it makes me shit, and sometimes real bad.  Doesn't deter me from eating it, but sometimes (not always) I come to regret it hours later.

Being Chinese, could lactose intolerance be the problem?  I have switched over to lactose-free milk and I haven't had the bloating or diarrhea since, at least as far as I can remember.  So I am trying the same with this lactose-free ice cream I bought, uh, last week?  Had a few scoops out of the box late last night to celebrate Memorial Day and ... well, I'll tell you I popped a little last night, and I feel something in my gut right now, but no bloating ... ?  Is it possible that my intestinal distress is not just the lactose but also the casein and the whey in the milk and ice cream, in which case I need to go dairy-free and not just lactose-free?

I'll see how I feel at work.  Then I'll need to get back to eating the ice cream -- which is delicious, by the way -- and see if my gut is telling me this ain't workin' either.