My Teenage Son Had A Viral Infection About 3 Weeks

My teenage son had a viral infection about 3 weeks ago. Had a high fever and lingering cough. He saw his doctor and got cough medicine and the rest had to run its course. He was doing much better until about 3 days ago and is very congested an his ears are popping. He also has a rash on the inside of his elbows and back of his shoulders.