Making the transition to milk with a lactose intolerant baby?

My son is ready to make the transition from formula to milk. He is on Isomil soy formula so when talking to the doctor and the nutritionist from WIC I kind of figured he would transition into either soy milk or lactose free milk. Well they both said that most babies grow out of their lactose sensitivity by age 1 and that I should start adding 1oz of whole milk to each of his bottles and increase it by another one the next day. Well we tried it and he ended up in the emergency room after the first bottle, because he couldn't stop projectile vomiting. I called the doctor twice yesterday and still have not been called back and I am basically stumped on what to do. I went back to formula and he seems perfectly fine. Should I try lactose free milk or what? He obviously is still sensitive to lactose.