If anything, I'd call the vet and bring in a stool sample to the vet just to be sure.
Fast him for 24 hours - he won't starve and that'll give his system time to re-adjust. If you feel you MUST feed him - only give him 1/4 cup of rice/burger mixture twice a day - enough to quell the hunger but not so much as he'll poop.
I'd cut down on the late night feeding as well - feed twice a day at consistent times (within and hour or so). My dogs are fed between 6:30-7:30am, and again abetween 6:30-7:30pm. If we have classes, they are fed after class but that's one night a week, and we get home at 8pm.
I came home today to Baron puking in the living room - looked like rice/carrots/celery, some of his breakfast and who knows what...oddly enough EXACTLY like the chicken noodle soup that my mother in law made the other night...although they deny feeding it to him. I suspect my brother in law may have given them some soup along with their dinner last night - it was way too salty for me to eat - I can only imagine what the dogs felt about it!
