It would be best to ask the advice of your vet Elaine. Not all flea treaments treat the same species. It may not need a visit with the cat but if you explain all that you have here, to the vet, he'll tell you what is the best to treat these sticky bugs. You say he is treated but maybe it wasn't with one that will get rid of this specific problem and your vet will recommend soemthing else. Flea and worm treatments can be fatal if overdosed, so consult your vet and tell him what you've used so far.