6 Month Old Tibetan Terrier Randomly Shrieking

I am the owner of a 6 month old Tibetan Terrier, Bodhi. Bodhi has been acting different lately. About a week ago, he started to randomly shriek in the apartment, as if he was in pain. We took him to the vet who cleared his anal glands and he said that was probably why he is shrieking.

Bodhi is still shrieking randomly, though, and it seems like he is having difficulty pooping. We can't seem to figure out if it is psychological or physical. He just doesn't seem himself. He won't eat breakfast and lurks around the apartment and sits by the front door hunched over. When we let him outside he seems to feel better, but he has shrieked randomly outside too. We left a voicemail with another vet this morning who does house visits. We also bought some coconut oil to put on his food, which we heard would help with his bathroom issues.

Have you ever experienced anything like this with other puppies/dogs?
We feed him a raw diet for breakfast and dinner. Usually 2 chicken thighs with bones or some pork ribs. We give him liver occasionally and sometimes a cornish game hen or chicken leg quarters. Lately he has not been eating breakfast, but does eat dinner.

Please let me know your thoughts, thanks!