 [ Symptoms ] i was in a bad car accident since then i commonly feel completely different [ Disease ] he is certainly old enough to have those other products but milk may not be the only issue behind the constipation problem you need to look at his whole diet you can try changing to soy or almond but do not be disappointed if this is not the magic solution i am guessing based on his age that he is picky so you will have to find a way of getting more fresh fruit smoothies  and vegetables in his diet his water intake should be high and keep using that miralax this is safe for long term use toddlers tend to stool hold try to keep from pooping because it is either inconvenient andor painful they can also be stealthy finding when they are having a challenging bowel movement this will eventually improve over time so hang in there