If he's fighting an infection, he would have abnormal white blood cell counts.
Antibiotics can cause a cat to become nauseous and not eat which is not what you want at this point. Especially to just throw in meds that may not be doing any good. How about an appetite stimulant?
Cat maid to:
Jasper, male Ragdoll ?? (approx 10 yrs)
Sweet Pea, female silver tabby DSH (approx 8 yrs)
Rose semi feral, a cpietra rescue, female tabby (approx 7 yrs)
Puddles RIP (1996-2014
Snowball RIP (1991-2005)
In a cat's eye, all things belong to cats.-English Proverb
“While we are free to choose our actions, we are not free to choose the consequences of our actions.” Stephen R. Covey