What can we do if the dermatologist prescribed the wrong medicine to my granddaughter?

My granddaughter went to the dermatologist for her scalp and a prescribed shampoo and prescribed medication was given to her on 10th day of the medication which was to be taken for 14 days. My granddaughter became ill with a fever and complained her throat hurt and she was dizzy when she stood up. She was spending the night with me. I gave her a fever reducer pill and a pop cycle and slept the night with her. The next day she still was going through the same thing as she did the night before. Except she had broke out into a heavy bumpy rash that completely cover her head to toe and her face was swollen and throat. Her father was babysitting her while her mother was at work so he called me to ask what to do. I said give her Benadryl she is having allergic reaction. Meanwhile the mother was called. She rushed home to find her with a 102 degree fever , dizzy, broke out head to toe with this bumpy rash. My daughter called the doctor’s office and he said to bring her in now. As soon as he seen her and ask what kind of medication she has taken. My daughter took all the medication with her and the doctor saw what she has taken. He said this was the wrong medication and this medication would cause Stephen Johnsons syndrome and he wanted to know who prescribe this to her. By the way she is 11 years old as of last month. The doctor (dermatitis) was across the street from his office . The doctor took the child and the mother over to the dermatitis office across the street. They went inside and asked him if he is trying to give Johnson’s syndrome to the baby. The dermatologist, nurses and doctor took several blood tests on her and told my daughter to put this cream on her and to keep taking Benadryl and fever reducer. And that they want to see her the next day and they printed off several papers from Mayo Clinic about Stephen Johnson syndrome and told her not to look at the graphic on the site if they went to their site.