If your 21-month-old daughter has had a temperature between 38.1 and 38.4 for 2 days, is holding her throat, and has lost her voice, it may be a good idea to consult a doctor. Fever is generally considered to be above 37.5 degrees Celsius when measured orally or under the armpit, or above 38 degrees Celsius when measured rectally. If her fever persists for more than 72 hours or if she doesn't seem to be relieved by standard treatments like Tylenol or Advil, it's important to seek medical advice. It's also important to monitor her symptoms and keep her comfortable.