justynaa,
Again, a continuous cough, even if it is not productive, needs to be evaluated.
There are just so many different possibilities that could be causing it, they all cannot be listed here.
Nonproductive coughs are usually due to an irritation of the airways of some type. But, again, there are many causes. The only way to know for sure what is causing the cough is to have it evaluated by a physician.
Good luck.