I take a Lactaid tablet in the morning before I drink my coffee o...

I take a Lactaid tablet in the morning before I drink my coffee or tea with milk in it. I get a sore stomach and feel nausea for about an hour or so, then it goes away. I get progressively better during the day. When I take a tablet with milk for dinner, it doesn't happen. I am wondering if it is the combination of the Lactaid pill and the coffee and the tea that is doing it. By the way, both are decaf!! So I am going to cut out the Lactaid and tea and/or coffee in the morning and see what happens.