It's not difficult getting the fleas off, but you need to treat the house inside and out so he isn't continually being bitten by them. Even with any of the chemicals put on or in him to combat fleas, they will still bite him. For in the house and the yard, use this:
Food grade diatomaceous earth for flea and tick treatment.
And then to keep the fleas from even getting on your dog, use products the flea do not like the smell of, and you can mix up yourself. Here is a good site for that, without the use of any chemical:
Chinaroad Lowchens of Australia - Ticks, fleas, bees, flies, snakes and other gremlins! And how to deal with them!
Since he's been bitten so many times already, be sure to take a stool sample to the Vet. now, and in two more weeks, then get a heart worm test.