Jack Mackeral (canned)
PB (put on roof of mouth with finger, see if he'll lick it).
Cheese (mine prefer sharp cheese cut in small bite size pieces).
turkey
Tramadol can cause nausea. Could your vet reccomend something for the nausea.
Just a thought -
If it were me, I might want to check with the vet to make sure that the medications are actually helping Buddy.
Not wanting to eat may be a sign the meds are not adequately taking care of his pain.