I wish my mom was as helpful for me in this as you are to your son. I think I'm a year older than your son (turned 19 this year).
For the first time yesterday, my mom actually began reading about EC on websites in Chinese. She briefly explained what some doctors said but we got in an argument because well...i was having a really bad day. She says doctors in China claim to see this all the time. Apparently they have classified 4 main types of EC. One type is caused by self trauma..
I will make a post later once I get the chance to have my mom translate the text for me.