Where do you buy wide shoes for your teens? His feet are a size 15 wide and i am struggling to find anything
Check Burlington coat factory they have bigger sizes and a lot of wide options
Nike online has wide shoes options
Sketchers or the work shoe store!
Also Jordan’s are made wider and new balance has a big selection.
You can also order custom Converse online in a wide. 
As far as I know you can go to Amazon