I was totally hoping for some good advise here - All I can tell you is I'm 31 - COVERED in eczema and I can't stop scratching

I thank god my baby doesn't have this!
I have one idea for you for on the potty - give him an ice cube (or ice pack) he can rub on the eczema. It feels as good as scratching - AND it actually reduces the inflammation and numbs the skin for a bit. If he gets to DO something it's a lot easier than NOT doing something. HTH!