I Have Been Having An Occasional Cough For 3 Months

I have been having an occasional cough for 3 months now. When I wake up in the morning I am a little wheezy but it seems to go away. I went to my doctor who ordered a pulmonary test. Never heard back so I assume that everything showed up okay. Also had a chest x-ray prior to the test. Nothing seems to show any problems, yet I feel heaviness when I breathe and still have an occasional cough. It is usually during the evening hours. Any suggestions?
I am frustrated and worried.