It sounds like all your kittens and adult cats are suffering from upper respiratory infection. Unfortunately, they are probably going to need antibiotics to recover.
I can see that you are over your head here.
I suggest that you call your local humane society and see if there are programs in your area for feral cats. With a program like this, you can probably get free medical care AND have all the cats spayed or neutered.
These cats will probably not recover on their own. Now you just have to be creative about where to find help for them.
Let me know if you still have questions.
