Can you collect disability benefits for brachial plexus?

My daughter was denied. It is strange tho because when SS wanted to determine her BP we were reffered to a Doctor Who mentally tested her. As you know, BP is not a mental condition it's a physical condition. The doctor was very confused (he said) of why they reffered her to him if she has no mental delay. She had to be seen by a different doctor. I asked SS they said it was no mistake but I said I would hire a lawyer so they gave in and sent her to another doctor to check her physical condition. Guess what, she had met her milestones, thanks to her therapists. Like tying her shoes, button pants etc...she was denied. I plan to go back and re-apply since my daughter is older now and going into surgery. Her arm will be a little limp and she will have to work hard to get strength and mobility back. The government doesn't want to be giving more money so they easily deny. What angers me is that I have a friend who has a friend who was hooked on drug, he then lost his mind....his family applied for SSI because they claimed he was mentally challenged. He got it. He spends it on more drugs and alcohol. He is 40 living at home drinking 24/7. But my bby gets nothing...according to SS