Re: Switching to milk & rashes??
Not sure what the rash is like, but here's my story:
With my now almost 3 year old, we slowly switched to whole milk from a toddler formula after he turned 1. Once we got the point where he was getting abut 75% milk and 25% formula, he'd get super bad diaper rash when he had a BM. It was like it was burning him. We went back to the formula and waited several months before trying the switch again. At about 18 months we were able to fully transition to milk. He was just on a regular toddler formula so nothing lactose free or anything so the Ped was a bit surprised by his reaction.
DS2 is almost 1 and we'll do the same for him, probably keep him on the toddler formula for a few months past his 1st birthday.