For the last two days my 2yr old cat has been very quiet, just sleeping all day. He is eating, but is just not himself. He usually spends quite a few hours outside, but hasn't even ventured outside since Saturday. He just looks really tired all the time. Any ideas what could be up with him? It is unlike him to be so quiet, he is usually picking on the other cats. I'll try and get an appointment at the vets tonight.