Update: just got to a vet.
My vet already told me to brace myself. All my cats are positive. He prescribed me some vitamins and antibiotics, saying this might help and might make them survive, but I should get ready for the worst. I'm fucking broken right now. I hate that I'm poor. I wish I were a millionaire and could just confine them all in the hospital, but the payment per cat a day in the hospital is legit 10% of my salary a month, and I have 4 of them. I hate this.