Hello S.,
In my opinion regression is never good. And your son, is at the age where he is constantly testing his boundaries. This act of defiance or desire of control will continue, not because of being mean, just trying to understand himself and the world.
Have you asked him why? He certainly has the intelligence to have an answer. He may need to be treated more grown up, instead of potty, say bathroom like a big boy, like daddy. Help with the mechanics of wiping, maybe he got raw or something. How could any of the changes you stated affected his confidence in going to the bathroom?
One of my son's was advanced. We were eating at a restuarant, around the age of two, when he said he needed to go to the bathroom. So I took him to the bathroom. And this started a huge scene, he didn't want to go to the ladies bathroom, he wanted to go to the men's bathroom. Well, there were men coming out of the men's bathroom, they offered to take him in for me, and he wouldn't go....And I didn't know them. He wanted me to go with him to the men's bathroom. So I tried to talk with him, reason with him, but he was set on what he wanted to do, and he was right. He just didn't understand why I couldn't go.
And through the years, there were numerous instances. What I learned was to try and see it from his eyes. Your son is a highly advanced 4, 5, 6 mind in a 2 year old body. Imagine what that is like!
Hope that helps! Many Blessings to you and your family while overseas! D.