Also... When we first got Simba and had flea problems with him, our neighbors put a few drops of Tea Tree Oil in his puppy shampoo and the fleas went away.
Of course, you'll have to treat the house and yard for fleas, but the tea tree old completely got rid of the problem with him.

It's also natural, so if using a shampoo that is "tearless", it won't hurt the dog's eyes (according to my neighbor) Of course, that doesn't mean not to be careful while using it.