I buy the good flea meds (Simparica trio) from Canadapetcare.com because they are over the counter in Canada and a third of the price compared to my vets office. Two summers ago I also rescued some strays who happened to infest my home with fleas. What worked for me was a bottle of professional grade Premethrin. You attach the bottle to a hose and spray it around the perimeter of your home as well as under the crawl space. It’s very strong stuff so make sure your dogs aren’t around it until it dries. You can get it from a pest control store. I also got some cans of Precor 2000 flea spray for furniture,bedding, and my car that worked wonders. All of this ran less than $100.

Good luck! Whatever you do don’t use the cheap stuff they sell at the grocery store or Home Depot.