My son, age 3, has had cold like symptoms....difficulty breathing thru the nose, some coughing, difficulty swallowing. I brought him to a walk in clinic. They checked his ears and saw inflammation in one ear. He was prescribed 50mg amoxicillin 2x a day. Today, I noticed that because he continues to berth thru the mouth, his tongue has blackened and he appears to have little to no saliva. What could be causing this? He is 34lbs. and has Prader-Willi syndrome.