Suggest Remedy For Cough After Having Tonsils Removed

Hi my son just had his tonsils removed on 12/31/14 before the surgery he was known to get croup at least 8 times a year.. Well right when he awoke from surgery his barkish cough appeared.. Now he s consistally coughing and sound like fluid.... Should I bring him to the E.R he has drank less than a 20oz bottle of water in 29 he s.. He refuses his medicine saying it burns, doesn t want ice pops... No apple sauce nothing... I m getting nervous.... He s also complaining of having a really bad headache Maybe I am a perinoid parent. But an answer would be awesome