Flu vaccine caused major complications - malpractice?

My mother got a flu shot at Walgreens in Carrollton just a couple weeks ago. The nurse asked if she was sick, but she did not make any other inquiries to determine if my mom has a weakened immune system. It is now my understanding that those with a weakened immune system (which she has) do not respond to the flu shot with anti-bodies; they only get sick. Only 2 days after getting the shot, my mom was hospitalized with breathing difficulties, pain and fever and now has a $20K hospital bill and an asthma diagnosis. It's my opinion that a more thorough evalutation of the patient should be required. Bottom line - they can't just go around shooting everyone up with viruses and not be held liable. This is disgusting and we need to change this problem. Can anyone help her?