I have a teacup chihuahua and he is about 10 years old but, seems pretty healthy. Lately he has just been sitting in our kitchen only at night. Completely doing nothing while nobody is out there with him. I have gotton up before at night to get water and i see him just sitting there not even blinking he seems to be spaced out. Should i take him to the vet? Is this a sign of a sickness?