Heart palpitations from dairy consumption, could it be lactose intoleranceo or an allergy

Maybe: The heart often reacts to whats going on around it. While its not the primary problem the heart can go fast when the body is stressed. This is called reactive tachycardia. A holter (if symptoms are frequent) or a 30 day event recorder ( if only happening a few times a week or month) would be helpful. Blood work along with a complete physical and possibly an echo of heart would also be part of work.