I Often Feel Like I Have Something Lodged In My

I often feel like I have something lodged in my chest and I have to cough to try to clear it up. I have been tested for allergies three times and each time the results are negative. My doctor states that my allergies might be causing a false negative. I also suffer continuously from sinus infections. I am beginning to think that I might have something going on with my lungs, how possible is this?