Flea infestation, HELP?

I have two large dogs (both labs) and I live in the deep south. Napoleon (my larger lab) has flea dermatitis and it is killing me watching him suffer. The fleas are out of control right now. I have done everything imaginable. We have been doing this weekly baths, daily vacuuming, weekly washing of the dogs linens and our linens, monthly front line application, monthly carpet shampooing and monthly treatment of the yard. I also comb them out about once a day (outside). I keep finding them though. Our mattresses are sealed in plastic and we regularly shampoo our couches. We do have a problem with feral cats in our neighborhood though, I'm pretty sure they have fleas because they are always scratching. They always come in our yard trying to catch squirrels and birds.We have called animal control about them several times but they have done nothing. Is anyone else having a flea problem, I am at my wits end. I do have a 1 year old son and want to keep him safe from chemicals (hence all the cleaning, vacuuming and washing). I have heard about the new flew pill Comfortis, has anyone tried it?