Treatment for Perseus and Apollo

It all started when I found fleas on my 2 sweet boys so I decided to treat them and my 2 other cats
Link our newest addition brought them in but he was treated 3 different times, given 1 dawn bath and they were still on him!
Reason for using Cheristin ^ because advantage 2 and revolution were used prior 
Little did I know that they would end up needing emergency fluids because Cheristin (flea meds) poisoned them even though they met the requirements for it 
Later that evening they became disoriented and would not eat or drink 
They were even limping!
I tried my best to give them what I could but had to take them to the emergency vet 
The vets couldn't find anything
They were dehydrated and had high fevers 
Ever since I dosed them they haven't been the same :(
This first treatment costed me 230 dollars with Elanco (flea med company) covering ONLY diagnostics, not to mention that I had to buy their prescription food separate
They got better for only a few days but now they seem to have a really bad URI and aren't eating as they should
They have also been really feverish 

I'm asking for this amount so I can get them fluids, treatment, prescription flea meds, vaccines as well as their neuter surgery for when they are better