My 83 year old Mother had a shot of Kenalog in her knee 11 days a...

My 83 year old Mother had a shot of Kenalog in her knee 11 days ago. Her knee had been sore for months, so the doctor drained her knee and gave her 1cc of Kenalog. She has experienced a severe rash over her entire body for 10 days and it is NOT going away. She has been taking Benedryl which a primary care physician prescribed after giving her a shot of Benedryl before she left the office. The physician said she always uses Kenalog and sees no problem with the drug. My mother is calling doctors trying to figure out what to do and how to make the itchy rash go away. With so many side effects this is not a good drug to take! Where's the FDA? Why aren't the doctors concerned about giving this drug?