Okay, I think I can help you. There is an oral product called Capstar that will do a complete kill on fleas in a matter of just a couple of hours. I would give her skin a rest and not do any more bathing or spraying simply because of the irritation and that is making her much more appealing to the fleas. You can get Capstar at most pet supply stores or online (just do a search on Capstar and you will see many resources for it). It is safe to keep her on it until you can get the flea problem under control. Treat your cat with Fronline, Advantage or Revolution - even though your cat doesn't come indoors, as she is probably harboring fleas even if you don't see them. Also, if possible, treat the yard as that is almost certainly where your dog is picking them up when she goes out to potty. Treating the yard is the best way to get rid of them totally. The Capstar treatment will give your girl's skin a rest and will take care of the fleas for a SHORT time. You need to repeat the Capstar frequently to keep the flea problem under control. I would also start her back on Frontline once her skin has had a chance to heal up.
Please let me know if I can help further.
Canine Health Care & Guidance
Qualified by many years of healthcare & experience in breeding dogs