If you can't afford the vet visit or the flea medication sold by the vet, try applying for Care Credit. Here is more information:
Over the counter flea meds are not effective, as you found out and in addition and more important, many cause cats to have very serious and sometimes, fatal adverse reactions, so I would never buy these meds in pet stores or supermarkets, etc. The biggest offenders are Hartz, Sergeant's, Zodiac, and many others.
In my area, they do sell Frontline/Frontline Plus and Advantage/Advantage II in Petsmart, Petco and Pet Supermarket, so I would suggest trying to find something like Advantage that you can buy over the counter from a reputable store.
There are two things you must do to eradicate fleas; one is to treat your cat with the right product and the other is to treat your home. Food grade Diatomaceous Earth (DE) can be used to sprinkle along baseboards and on carpets. It is not harmful to humans or pets and it will kill adult fleas, larvae and eggs. If you would rather get an exterminator that specializes in fleas who can treat inside and outside areas (if applicable), that would be best. Fleabusters is a good company and they're nationwide, so hopefully there's one near you. I used them personally and was very pleased.
I would not recommend putting their products on your cat, but using them to treat your home.
An exterminator who comes in and sprays around is not effective and is using a pesticide/insecticide that IS harmful to pets and humans.
I hope everything works out for you and your Polo!
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