nasal draining

For sometime now ( 2 years ) my sinus drain excessively
when I exercise.  I have gone to a number of doctors
and they have prescripted sinus medicine but nothing
has help.  Results of all this draining causes me to
cough excessively and that gives me a sore throat.
The problem is getting worst, to the point that I can not
even go for a walk without coughing.

[National Jewish]

This is a common symptom for something called Vasomotor Rhinitis. When you increase the blood flow in the nose, there is increased "leakage" from the blood vessels and thus the runny nose. An atropine nasal sprays sometimes works for this.