What Causes Sickness, Body Aches, Sore Throat With A Bad Mouth Taste?

My husband has been sick for the last couple days. He went to the doctor, they swabbed for strep-that's not it. He has body aches, his throat hurts and he says it feels like there's a ball in his throat, he had a fever but it's pretty much gone now. He was having cold sweats and chills and he says that every time he swallows he gets this awful taste in his mouth that kind of tastes like burnt popcorn! What could he have and how can I help him?