My roommate has a year old rescue. The past three nights he has had diahrea at night only. During the day he poops normal. There has been no change to his and my dogs diet. The only new things are going to the dog park and he is sleeping in his kennel again. he used to always sleep in the kennel but she started letting him stay out. he is back in as he gets into things at night. Now he is having the runs in his kennel and it is getting all over the wall and carpet. what could cause this as nothing is wrong with my dog.