Lactose Intolerance

My son just turned 2 and all of the sudden he has become lactose intolerance causing vomiting and diarrhea on his first week on transition but now after 2 hrs of feeding or twice a day of watery to loose BM. The BONAKID and Promil Gold Formula keeps on changing adding skimmed milk, Lactose etc. and now I'm resulting to change to NAN AL 110. Have you experience this also? Please do share.