Hello
and
to YT. "Yorkies For Dummies" is the first one I recommend."Yorkshire Terriers: A Smart Owners Guide" is the second book. These are excellent resource books. And we have a great amount of info here.
It sound like he is constipated I would suggest to put plain canned pumpkin ( not pumpkin pie mix) in his food. Also it should help with the poop eating. If it doesn't help with the poop eating then give him a little pineapple. Good luck