Suggest Treatment For Chest Congestion Along With Cough And Fever

HI, My 11 year old son has been sick for 7 days now. It started out with a horrible congestion, cough and high fever. The fever then lingered on for 4 days, but only between 100-101. He no longer has the fever, but is very fatigued, hasn t had any appetite and is still coughing and has congestion. I ve never seen him sleep as much as he has this week, for this long. He said it s a chore just to walk down the hallway. I brought him to his pediatrician on day #4 and they did a strep test, which came back negative. They didn t do any other tests on him. Just wondering when I should bring him back in to the doctor, or how long I should wait this out? Thank you.