I really need help...

I bought my BP from a pet store about 2-3 weeks ago....I noticed one or 2 black little balls on him a few days after having him and searched what it could be...mites! Well, they told me they fed him the day before i bought him and not to feed him for 1-2 weeks it was up to me. I noticed more mites and bought a spray but didnt take out the substrate...today i took out everything but 1 hide and paper toweled the floor, i put him in light soapy water and cleaned the entire cage. The little guy however is really really weak. I mean like i put him in the water and his head went under...he is limp, so i quickly picked his head up and placed it on the ledge and let him stay in there for a little while i cleaned the whole cage. A bunch of mites died in the water and from what I could tell there is none on the snake anymore and nothing in the cage, I know there are probably eggs. I do still have the spray which i will use every 3 days like it says....i'm thinking about also using the Provent A Mite that many people here say to use. I'm thinking about 90% of them are gone, but he is really weak and looks skinny....i tried to feed him this morning and he didnt go for it. What should I do from here to keep him alive? I really don't want to lose this little guy and I guess this is a lesson learned to not buy anything from a petstore who doesnt care about its animals.

I think you should take the lil guy to a vet asap. There could be other things going on, like internal parasites, that you can't see on the outside. The vet may also give you advice on how to get the snake's strength up to the point that it can eat prey items.
Other than that, I know it's a huge debate among keepers, but I personally wouldn't use anything other than Provent A Mite.

Sarah nailed it. Get yourself some P-A-M and that'll get rid of the mite eggs you can't see. Good job getting rid of the live ones in the meantime, though. And find yourself a vet who is experienced in dealing with herps in general and snakes in particular. Internal parasites will sap the nutrients even if the little guy is willing to eat....or...if the mite infestation was bad enough, he could actually be anemic.....or....there may yet be something else going on, like a respiratory infection. Only a vet will be able to determine what's going on and give you the best course of treatment.


Here's a couple of links to help you find a qualified vet in your area:

http://www.arav.org/USMembers.htm

http://www.anapsid.org/vets/index.html#vetlist

Good luck with the little one!!