Using Brewers Yeast On Dog's Coats For Fleas

I am so sorry for writing so much about fleas but geez, it really can get annoying trying to find the right method of dealing with them. My chihuahuas are so special to me and I want them to be comfortable. About 3 or 4 days ago, we treated our yard, even though they never touch their feet on the grass, we treated it anyways. I also cleaned the house from top to bottom, washing all the cushion covers, dog blankets and such. We also tried that spot on treatment by adams. Well, that worked,but only for a couple of days. This morning I found more fleas. I got out the brewers yeast, you know, the one that you buy at the health food store (not the bakers yeast) and sprinkled it all over their coats. Those fleas just jumped off of them. Maybe if I continue this, they will be flea-free for awhile. I feed them top quality food, so I don't think it's that. Guess it's another trial and error here to see if it's going to work. Wish me luck!