Can you get a dairy intolerance at any point in life? I’m in my 20s and my stomach has been HORRIBLE for months, I haven’t been able to figure out what or why.

I just ate a bowl of cereal, felt fine before it, now am having HORRIBLE stomach cramps, that feel like I’m about to have diarrhea.

This happens a lot but with bigger meals and haven’t been able to pinpoint what caused it.

How do I go about testing to see if it is dairy?