My Husband And I Both Relatively Healthy And Have Had

My husband and I both relatively healthy and have had drainage and chest congestion. I caught it 2 days after him. Therefore know it to be contagious. We have non productive coughing and chest congestion. Tired and headaches. It keeps appearing to be getting better but then it comes back. We have had these symptom's for 2 weeks. The doctor said it was a virus / cold and we are taking decongestants per the doctors orders. Why does this keep coming back after it seems to get better? Could we have mono or something that needs antibiotics? No discoloration in the discharge or saliva.