I just got done with a flea issue but it was never really bad, but enough to be annoying. Our dog is only outdoors to potty and exercise and she was on Frontline Plus religiously and she STILL got fleas. We bathed her and used every at home treatment we could find both in the house and outside. I even bathed the cats (that was interesting, I've never heard those sounds come out of a cat before) and treated them since they even had fleas too even though they are solely indoors.
I ended up switching our dog to Advantix too and we called a professional exterminator. I called 2 places, one was a big name one and they quoted me over 200 for one treatment with a 75 dollar 'follow up' a month later and no guarantee! I called a smaller local place and they charged 140 and they would come out as many times as i needed. They said they didn't treat outside but to get some Sevin and spray it in the yard. It is soooo much cheaper than all that special flea stuff and I really think that helped our yard, not that we knew where it was coming from but our backyard is shady and buggy in general and now its not (we used both the spray and i got the powder and doused our porch and let it fall between the cracks). They treated our house once and we noticed less and less but then suddenly she started getting more so I called and they came back out. I also called Advantix, mad because I had just put it on her less than 2 weeks ago and they were increasing by the day and isn't it supposed to 'repel' fleas?? They said Advantix was safe to apply every 7 days. So I applied a second dose to her and the house got treated a second time....and a week later. No fleas. *crossing my fingers*
I did the lemon thing and I don't think it did anything. But it did smell nicer than the chemicals! I also tried the garlic and I dont think I gave our dog enough but what I did give her did nothing. Our cats didn't eat it even when mixed with wet food. I didn't try the salt thing but I did try sprinkling Borax on the carpet, letting it set then vacuum it up. Its safe for the animals as long as they dont eat it.

I am not sure how much it really helps but it makes the house smell good and I've washed everything fabric in our house at least once since this all started and washing with Borax is supposed to help too.
I am sorry you have to go through this. I know it was a very stressful few months for me and I hope I am finally done with it. Let me know if you discover something that works miracles!!!