We moved twice in a few months - The first time it affected Rays diet, but the second he was fine....
What I did was cut his walks out or down, if he's not eating and walking he will lose more weight - wait until he has gotten in to a routine before long walks or runs.
Add some protein in to his diet, try adding things like veggies, pasta, raw mince, anything to bulk up the diet
As for leaving his food and getting distracted we take anything off of ray if he hasnt eaten it within 10-15 minutes, that means he begins to get usesd to having to eat or it will get removed, it forces him to stop being so picky because before if Ray didnt eat his beanies i'd give in and give him something super tasty that he'd love (Tuna) so he began just waiting it out knowing id give in. When i stopped giving in he eventually realized that if he didnt eat it he wouldnt get it...:D
I feed ray as often as he is hungry, 7am he will get two eggs boiled and kibble, 10am kibble, 12/2pm raw chicken mince, beef mince or tripe with spinach and garlic and kibble, 6/7pm or whenever he's hungry at night he will eat away at kibble.
Try boiling some chicken breasts, when Ray was ill as a small pup that was the first thing he ate and he devoured it! Just two chicken breasts boiled and cut up into chunks will give him his appetite back!
good luck!