Chronic cough. Is it anything serious?

I have chronic cough it is not continueous but i get it twice a day or once a night for a couple of hours which is clear phelgm cough i try to get all of phelgm out they i feel relief it all Started three months back since i was getting treatment for my sinusitis i never had wet cough in my life its soo bad when i laugh i cough when run( i Start coughing when i am in the class or any other silent place i start coughing this happens to me since childhood)when i breath deeply i start coughing and when i bow down and breath i start coughing when i get phelgm i get it again and makes sounds in my chest gurrgurrrr when it comes out then i feel good now its better than the last month but i still have it what should I do i have taken a lot of antibiotics and bro zedex surup and the surup really helps me.....is it anything serious