Questions about my bored puppy and dealing with his loss of appetite (Long post)

#1. Bored puppy, is he okay?

I work from home and my pup (7 months now) is with me all day. He seems to be EXTREMELY bored when I do not pay attention to him. He has been showing signs of depression. I feel really bad, but a few months ago when I would play with him every hour, my work suffered.

The new schedule has been to wake up around 8, feed him and do drills of tricks he knows well, ignore him while I do some work, then 9:30 take him for a short walk and a 5 minute playtime. Then ignore him from around 10 - 2 during which I feed, train, and take him on a walk again, then short play time and repeat. Once my SO and I are off work, we play with him, he gets another walk or goes to dog park for an hour twice a week and he seems okay. But for the past week, he wasn't as playful, didn't want to play fetch, ate less, slept more. (Depressed?)

So recently, more than before, he'll cry and throw tantrums until he concedes that there will be no play time. Then he will alternate between pacing and whining, taking short naps and staring out the window/barking at passersby. He doesn't like to play with his toys or watch tv. The only things that really preoccupy him are chews, but he'll finish a kong or bully stick in under an hour, and I'm worried if I give him more than one a day, it'll further lower his appetite, or just spoil him for too many "treats".

Is my current schedule okay? Should I be giving him more chews? Is there anything else I can do to keep him entertained, other than sending him to a daycare with other dogs?

#2. Punishment for not eating For the past week, pup has had a loss of appetite. Breakfast and lunch, he will not eat. I think it partially could do with the fact that during the weekend, I gave him some wet food after he finished his dinner, and I've posted here about him being a picky eater multiple times. I started giving him 20 minutes and taking the bowl away. He barely eats anything, and my boyfriend hand feeds him dinner so he doesn't get too hungry.

I started leaving the door to my room closed until he finishes his meals, instead of waiting the 20 minutes. It worked for three days, and he finished his meals, but was ineffective today.

Is there anything wrong with this closed door method? Should I really just be letting him skip meals if he doesn't want to eat?