can mms cause a dry skin and or eczema

One possibility might be a fungus.
Athlete's foot is a fungus.
If you apply MMS spray and it makes it worse, then stop applying MMS.
Aztec Clay mixed in equal parts with Vaseline is suggested to remove this fungus.
I don't know if this is the case with you and others probably can explain it more clearly.

Otherwise, I have never had MMS cause dry skin for me and I have been using MMS for 3 years now. I use it almost every weekday. That's just what works for me.
This time of year though, my skin usually gets dry because the cold sub freezing air outside does not support moisture and skin gets dry.
Also with the heat running while inside, that dries the skin too.

My skin itches this time of year. I tried the Aztec Clay last with Vaseline last week and got instant relief.

Edit: just to be clear. I probably had two things going on. Dry skin and the Aztec Clay and Vaseline helped, indicating possible fungus.

Aztec Clay is not expensive.

Sometimes Vaseline alone helps with dry skin.