More than likely your baby has ingested something that has not agreed with him or he has worked himself up with stress while you were gone. By doing this or eating something wrong he has thrown his GI tract off. I would feed him a bland diet for the next few days made of boiled chicken or ground beef and rice with some plain yogurt added to it and some canned pumpkin (not the pie mix). This should help balance everything out and give his GI tract a break. Once things go back to normal start to gradually add his regular food into the mixture until just his regular food is left. The reason for the gradual awitching is to not throw his GI tract back off again. Usually dogs gave this imbalance when food is switched over too quickly or due to stress. If his condition gets worse or does not improve then I would see a vet for a full work up and exam. I hope this helps some but if you need anything else be sure to let me know.