one thing to understand about bullies is their systems are kinda sensitive and so you try not to do to much switching around of foods esp if they are young. its possible the beef is not agreeing or could be any number of things. i would put him back on the pork and applesauce till his system calms down. if he does not get better then you can do a bland diet. chicken and rice since beef could be causeing the problem. keep giving him pumpkin also. maybe cut out the biljac treats also till he is better and possibly look for a better treat as biljac is not a high rated food and im assuming the treats are not much better. keep us updated.