Lactose introlant

Hey girls so I’m trying to to self diagnose myself but I think I may have an intolerance to dairy . Mostly every time I eat ice cream especially m&ms any of the sort that contains dairy I feel gassy and my Stomach hurts and cramps and I get nauseous I’m trying to ease my way off dairy but I enjoy it a lot . I’m basically a vegetarian I hardly eat meat I only eat dairy products and veggies .