K.M.
Hi. I went through the same thing with my daughter. Well actually she has a milk allergy. A milk allergy is when they can't process/digest the protein in the milk. Lactose intolerance is a sensitvity to the sugar that is in cow's milk. I wound up having to put her on really expensive formula ( Nutramagin, i think I spelled it right lol) and she still had problems. Maybe try good start by Carnation. I've heard a lot of good things about it and it's cheaper than the stuff by Infamil and Similac.