If she's had fleas for awhile then you will need to start an aggressive line of treatment, unfortunately. You will need to treat your whole house (carpets, upholstery) as well as her.
You can bathe her to get rid of some of the fleas and itching. If you see fleas crawling on her, you can use blue Dawn soap. If you don't see fleas and she is just itching, I would recommend using a shampoo with anti-itch ingredients like oatmeal, aloe vera, tea tree oil, etc to soothe her skin. Do not use human shampoo.
There are also sprays for "hot spots" and itching, I personally like to use the flea itch spray listed here:
Dog Products | Veterinarian's Best: All-Natural Products for your pets' health., although it is a little pricey. (The site has a coupon for $3 off on any product though.)
You *may* be able to treat this without a vet, but you'll probably have to spend around $50. I would buy:
- a powder to treat your home (around $7),
- 1 dose of a flea treatment ($12-$18) to get rid of the current infestation
- possibly a shampoo or Dawn if you don't have it (around $8)
- an anti-itch spray since her itching seems to be bad ($7-$15)
And you say you have a flea spray so I would continue to use that.
Unfortunately I do not see a cheaper solution to this problem as it seems to have escalated. I understand times are hard and pets are expensive - but using a monthly flea preventative will save a lot of time and money down the road. Now you and your dog are suffering.