DS loves to scratch his belly during diaper changes. We try to keep his nails cut as short as possible, but he's constantly scratching himself. Normal? It's like an instant thing-onesie unsnapped and pulled up to access the diaper=DS scratching his belly.
Does he scratch where the diaper elastic was? Maybe it itches there, especially if it leaves any marks on his skin? Could you try to put some lotion on his belly?
With all of the weird weather changes, my kid has been scratching his butt cheeks the moment the diaper is opened for a change. I try to lotion him up as much as possible since I think it's just the dry air. He does have mild eczema on certain spots too, so we use Aquaphor or Eucerin when necessary.