Have a stray kitten that recently adopted me. Unfortunately, he has "Leukopenia which is a very low white blood count and means he is like a bubble baby that needs to be protected because he can pick up any and everything. He came with a load of flea passengers which is the last thing his blood/immune systems needs. I swear the fleas here in Florida have a big red "S" on their chest because these little suckers are unlike any fleas i have ever encountered - they refuse to die. I have spent the last couple months trying every and anything i could think which included giving him 5 baths and using a dry vac on him. ( he likes both now lol). I even resorted to using those monthly chemical poisons prescribed by a vet because i figured i would be able to correct any harm to his skin/organs via foods/herbs once i eliminated the fleas. Turns out, that poison that i put into his system had very little effect on those blood suckers and i was about ready to shave him to get rid of them. I finally located an all natural non-toxic product that is safe for human and animal when scouring the web for the umpteenth time that worked instantly. WONDERCIDE is a "shark tank" winner that i highly recommend - the stuff is amazing and the kitten got to keep his fur!! https://www.wondercide.com/ Back to add - Wondercide has several solutions and if using on a cat then you might wanna bypass the solution with peppermint oil because can be toxic to them. I went with the rosemary and cedar solution.
I hope everything is gonna be okay with your little guy! I also have cat that "adopted me", I understand your feelings