I never thought owning a baby bird would be any harder than owning a baby dog. I got my dog when he was roughly 14 weeks and he was okay but obviously, they are hardier animals. I've watched most of my budgies get sick and die within days (I never thought about taking them to the vet at the time), plus I have done some research, so although I do recognize most of the signs and symptoms of a sick bird, it was hard to tell with a baby, which was exactly what the doctor said too. I am in no way an expert on parrots but if the doctor couldn't tell what was wrong with him, I don't think many people can. I also don't know anyone in person who does own a parrot, which is a main reason why I am here. I need information from people with personal experience and I am so glad I have all you guys to get us through this.
Liz, I decided to check out the reviews for this place out of curiosity. Although there were very few, most people were happy with their birds. However, I noticed a bad review saying their parrot got sick within 2 weeks of purchase and died very soon at the vet's office. Their problem seems very similar to mine as that customer complained that he sold him an unweaned baby, claiming that it was weaned, and soon enough, the bird got sick...
I didn't get a chance to bring the bird back to the breeder anyways, mainly because I didn't have the time after work to make it there before they close. I didn't want to anyways because I know they wouldn't want to keep a sick bird around with all their other birds. I took the doctor's advice and bought hand-feeding formula instead of using the grounded up pellets that the breeder told me to feed him with. Because Peanut is so skinny, I thought this would fatten him up a bit and give him some more energy. We fed him this last night for dinner and this morning he looks a lot better!! So there may still be hope for him!

He's been climbing around his cage, eating the seeds I left in one of his bowls, just overall, seems like he's doing better. I don't want to get my hopes up but I really really hope he will recover from this and that his illness is just due to malnutrition and nothing more.