the number one google search that leads to my corner of the intertubes is some variation of does ice cream cause stomach aches?
and judging by the sheer number of people wondering this and my own experience, my scientific conclusion is YES. YES ice cream causes stomach aches. no, you are likely not lactose intolerant, it is just tough for many people to digest including me and you, obviously.
so there, internet, is your definitive answer.