What's wrong with my dog? She's a very young pitbull like I think 5 or 6 months and I noticed she was getting skinny and wasn't eating or drinking water. I no she was being bit by flies on her ears and I didn't no what to do, but I tried giving her food today and she still didn't eat...

Has she been vaccinated, dewormed?
Is she having any diarrhea or vomiting?
If she is uninterested in food and losing weight then I would get her in to your veterinarian to be checked out.

I agree with LadySam. A 5 month old pits does about three things; eat, sleep and play. Bet she is only sleeping. Since she is losing weight I'd get to the vet now, could be worms or could be worse. We can't do much more from here but wish your pit the best.