There is nothing that says that the OP hasn't tried any of those treatments. The problem is that 1) treatments take a while to work and 2) If the treatments fail it takes a little while before you can try a new one. If you try an new one too soon you poison the animal which doesn't seem a good way to take care of the kitten. During the between times of seeing if it's working or waiting to try a new one, one would generally treat the suffering by doing their best to comb the fleas out.

Chibi, If first treatment fails to work Op should consult with a vet. Some treatments can be very harsh. I agree. Particularly with resilliant bastards such as fleas. My cats tend to throw up from that back of the neck treatment (that monthly flea and wormer all in one treatment) and pyrethrens as a wash, while it does the job well, can make a cat unstable on it's legs, drool or throw up when it licks the treatment off it's fur. If you are going with pyrethrens make sure you let the treatment sit while the pet is being washed for a good 5-10 minutes or until you see fleas start to fall off and die in the shower or tub, then rinse all of it off thoroughly.

Used this pyrethren wash (Fido's flea and tick rinse) on an extremely starved kitten i found with a severe lice problem. Found it a good home. Kitten is doing fine. The vet complimented me a week later with the new owner, on taking such swift action with the lice and for feeding her small portions slowly as not to do any internal damage to the kitten. It's a great product, But it has to be rinsed off.

That's an interesting story but lice and fleas are two different things. Compared to lice, eradicating fleas is a challenge. Pet lice is not an issue for humans so when clearing it up you only have to focus on the pet, and the areas your pet is prone to hang out. For fleas you pretty much have to disinfect, scrub, wash, or just plain burn everything in your home. The issue could be that the OP is clearing them off the pet but keeps missing some area in the home causing the pet to keep getting them. It could also still be the same situation that my sister was in not too long ago when her dog had fleas. She used a product on the dog that didn't work the way it was supposed to and the veterinarian told her she had to wait a while before she could try a new topical treatment. The reason being the dog having sensitive skin and not wanting to many chemicals on the skin because the other was not made to just wash off. It was a rub on and leave it. All I'm saying is that you shouldn't assume that because the OP has a continual flea issue, that they aren't trying their best to help the kitty. Different medicines, different pets, different responses to the medicine.

Capstar works within 30 minutes. Dead fleas everywhere. Works for a day or two then you might have to dose again. Australian here.