Hi there. I posted on your other thread as well.
I agree with the other ladies, just give it to her at all once. No need to slowly change for that type of switch.
If lactose is the problem, then you should see a difference after a few bottles.
Personally though, I think you should talk to your doctor about trying Soy or Hypoallergenic. It sounds to me like she could be having some problems with the milk protein itself and not lactose.
Please update us on your visit tom. from the doctor.
Wendy