yea i'm going through something like that too dude, my dog of 10 years just recovered from cancer surgery but he's showing his age now, he can't even jump for cheese! (2 months after surgery), he can't even walk for more than 5 minutes (i used to take him out on 2 , 30min walks everyday), 2 days ago he just collapsed while out on a walk, i carried him home, vet said he's just tired and old.