I Have Been Coughing For Over 4 Weeks Now From

I have been coughing for over 4 weeks now from dry cough to productive and then dry and productove again. My doctor had my blood checked and no signs of bacterial or viral infection in result but she noted that allergy indicators in my blood are at a high level. She oredred xray and a few days after the result came. It shows that I have a suapicious right infraclavicular density i am worried. Can anyone tell mw what could this be? I will for sure be back to my doctor and also wants to ask that here as well.