Solve the constipation problem????

Is it that the formula milk PediaSure had improved the constipation problem or is it due to change of milk?

Mother had tried 200g of PediaSure on Ethan as doctor said some of the children don't like to drink this milk because of its taste. Luckily Ethan accepted it. First we thought that after drinking this milk, Ethan will pass his bowel movement. But we waited for 4 days only to get him to do his big business. After 4 days and having finished the whole 200g of PediaSure, we have no choice but have to change back to Progress Gold. This is because mother didn't stock the PediaSure and also still left one tin of old formula milk. After changing back to the old milk, Ethan started to pass his bowel movement everyday. Mother didn't know whether is it because of change of the formula milk or the result of PediaSure.

But mother thinks that it should be PediaSure's effect. This is because so far Ethan drink the existing milk there is not any improvement of the constipation. It cannot be because of changing back to the old milk solves the problem of constipation. So mother just let go of buying the old formula milk and switched to new one. So now just wait and see. Well, actually also no choice because we have already stocked up PediaSure.