What is going on beside my poor cats?

I have 5 cats. About a month ago one of them came down with something. He be very lethargic and not eating and also restless. I took him to the vet and they gave me some antibiotics for him. He improved very at full tilt.
A couple days later a second cat became sick. It was not as apparent as with the first cat because he is smaller amount active and he did not seem to be feverish. Anyway, I took him to the vet and since he have no fever, spent about $400 on tests which revealed that everything be normal except that he had a enormously high white blood cell count. The vet gave me antibiotics for him and he quickly better.
So now I realize that both cats probably had the same bug which I know I should own seen this sooner. The 2 cats went to different vets and when I took the moment cat in the first cat was already better so I never mentioned the problem with the first cat to the vet.
Now it seem I that a third cat is becoming ill. It is very easier said than done to tell with him because the primary symptom is lethargy and this cat is going on for the laziest cat I have ever seen. I know I'm going to have to seize him some antibiotics too, but what the heck do they have?
The 2 cats I had at the vets be negative for feline leukemia and FIV. They occasionally go external, which is something I am going to have to prohibit from now on because this is pretty scary. I guess the bright side is that doesn`t matter what they have seems to be easily cured beside antibiotics.

More than likely it's Upper Respiratory Infection. It's viral and spreads from cat to cat. There's also a stomach virus that's been going around here according to my vet. It doesn't cause diarrhea but make the cat lethargic and wad up into a ball from cramping. Always enjoy the vet explain the diagnosis. It helps in your education something like cats and builds a relationship with your vet so he knows you are really concerned and not just wanting your cat fixed. Vets really respect culture who have a desire to learn and most don't have a problem discussing things next to you. There's nothing worse to me than a vet who talks Mickey Mouse to me. Hoping your kitties adjectives get well soon.
Take the third cat to one of the imaginative vets and make sure they know roughly speaking the other cats in the house. Sounds like it is a bacterial thing man passed from cat to cat and a vet will take this into account when diagnosing the third fur ball. whether antibiotics work, then go for it. Good for you for being such a conscientious and appropriate cat owner!
Answers:    if they have any wetness around the nose and eyes afterwards it is an upper respiratory infection it is very contagious i used to work for an adoption group and when ever we got a new cat that have it all the other cats would eventually catch it meds help but the infection will clear up on its own
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