Go get checked for allergies. I had this problem for about a year. I was miserable; PND, watery eyes, cough. Ended up being environmental allergies. No medicine worked (this happens in about 3% of people, lucky me), so I opted for the shots. Didn't hurt, like a pin prick. 3 months later, my symptoms were gone and I have been fine ever since. I get a shot once a month, and that's it.
It is definately worth looking into. Medication just masks the symptoms; the shots actually fix the problem.