Hi welcome to health care ... You should avoid dairy product if you are having lactose intolerance .. For gas problem that is function bowel problem acid reducer drug can be taken if acidity associated ... For gas simethicone tablet or digene syrup that also contain simethicone can be taken.. If constipation present and severe enough than ispghula husk with milk can be taken for that... Avoid gas forming food like ... -Onion -Turnip -Cabbage -Cauliflower etc Take care Hope this will help If needed physician consultation for examination