unknown respiratory infection and a very frightened mom

I have rescued a very beautiful kitten about a month ago and since he had an eye infection (later diagnosed as Herpes) I started to care for his eyes, after 5 days he had a diarrhea which lasted for 9 days (I rushed to 2 different vets after the day 3 and they told me it's probably food allergy, anyway I was worried enough from the first day of bringing him in, that I quarantined him and did'nt let him have any contact with my other 2 cats(11 years old), although the vets told me not to worry!) after 3 weeks he was healthy and playing and eating so I decided that he is safe to be introduced to my older cats. But just 2 days later, he was less active and he collapsed while trying to play, I was worried sick and took him to another clinic and they told me he has pneumonia,they have started antibiotics... The problem is that I have seen 2 doctors in this clinic one has said the cause of pneumonia may be Herpes , one said it may be Fip! Little kitty doesn't have fever (he didn't even when he collapsed ) he eats, drinks, breathes fast(which I guess is normal for his condition?) , even tries to play. It's been 3 days now, he seems much better. but those doctors haven't answered me clearly about his case they say it should pass the 5 days of treatment before they can diagnose it more clearly, I want to know if it's probable he has Fip? If so, are my other cats in danger? They just sniffed him from 0.5 metre and once sniffed his litterbox,and once drank from his water(they were so afraid to see him that avoided to be in direct contact with him) but I have caress them after handling the new baby... I have disinfected the whole house and moved the kitty to my parents'. But I am very worried first for him and second for my older cats.

Sorry I know that this post is long and not well-written, but I hope someone can answer my questions!

Thank you!

FIP is impossible to definitively diagnose.  There are hallmark symptoms and suspicious lab test results which point to FIP.  Has your kitten had blood work done?  I think the more likely explanation is upper respiratory infection caused by the Herpes virus that turned into pneumonia.  

Kitties that have FIP usually have fevers that come and go for no apparent reason.  Wet FIP is the more common form and there is a very obvious buildup of fluid in the abdomen.  

I hope your kitty feels better very soon.

Thank you very much!
They have done CRP. And xray and sonography- there was no "suspicious fluid" in the abdomen. Also he is negative for Felv and fiv.

If he has herpes, will he recover? He is so young. Maybe less than 3 months... He breathes 70 times per minute while asleep , is it normal?
Could you tell me if it's anything I can do to help him? I give him high protein food and message his lungs and caress him so he doesnt feel stressful...

My heartfelt thanks again. I feel much better now and I think it helps the kitty too if I am less worried :-))

If he gets better from the antibiotic, and stays that way for several weeks, I would say he has Pneumonia from the herpes. If he has FIP he will most likely deteriorate and get ill again quickly.  As long as your resident cats are healthy, and currently vaccinated, that helps tremendously in not getting infected with the disease. You did right by taking precautions, make sure the litter boxes and that area around them are especially sterilized. There are a LOT of kitten illnesses that mimic this disease, so don't give up hope until you know for sure, what makes it so difficult is that there is no one test that diagnoses this horrible condition. I'll pray for your little one, that it is just a kitten illness, bless you for your concern and help/ 

Oh I see!... Thank you very much!
I have seperated them quickly and sterilized almost everything in the house!:-)

That your kitten has tested negative for those other diseases is very encouraging, and herpes isn't as bad as it sounds in a cat, it is a 'kitty cold virus' and is VERY common. Giving L-Lysine (I give mine as treats, found on Amazon) will clear it up, it helps by not letting the virus duplicate. Fast breathing would be common with pneumonia, and cats have a higher respiratory rate than ours, usually around 30/breathes a minute, but a nervous cat, like at the vets, could be higher.

 I just wanted to let you know that you have posted very early in the AM here, it is only 6AM where I am at (I get on at 5AM most mornings, the only time I have time  ) so if you don't get many answers, bump your post back up to the top of the list and where people can see it, by posting just a few words, There have been so many people on lately that have experience with this disease, I hope they can give you advise and support, good luck! PS I noticed Denice must be an early riser too, or is in a later time zone!

My heartfelt thanks once again!
Yes I live in the other end of the world! It's 16 pm here!:-))
I'll post it once more, thank you for the advice!