We have a three year old male neutered cat who disappeared on us for about three weeks. He came home earlier this week skinny skinny skinny, like he hadn't eaten the whole time he was gone. Well, within the first 12 hours he sneezed a lot but ate and drank just fine and slept a lot as well. And he has continued to eat and drink and sleep and move around pretty normally, other than he wants to be with us now all the time. Yesterday, one of the other cats knocked a jingle bell off the tree and made a lot of noise with it. Our male started breathing really heavy like he was scared but calmed down after a little while. Then someone opened the front door on which we have a wreath made entirely out of bells, and the cat panicked again and started breathing really heavy. Last night then he slept with my son and his breathing was normal and he ate and drank normally all day with no diarrhea at all, just normal stools. He even jumped up on the table where we feed them with no problems. By 5pm or so he was breathing heavy again and sounding raspy almost. Our vet is out of town and her partner, who only does livestock, told us that it sounded like he was getting a respiratory infection and we should give him antibiotics. I told him we had cephalexin and penicillin that we keep on hand and he said, sure use that. But he didn't say which one or how much ... it was after 5 when we called ... Any suggestions for how much of what to give him? We gave him a small dose of cephalexin just hoping it was right, less than 100 mg.