Exercise-induced severe sinus pain? Why?

I have recently started pumping up my cardio and afterward, for at least a day or so, I have severe sinus pain, drainage, headache and watery eyes. I used to have severe allergies, but I was given a series of shots over a period of 2 years from my allergist, which made me immune to most of the allergens I was allergic to. I KNOW that this recurrence is a result of the strenuous exercise. What can I do to prevent it from happening again, besides stopping exercising. I'm reluctant to see a Dr. because most of the doctors online seem to have no idea as to what the real issue is and therefore, don't know what to prescribe. Maybe someone out there has tried something that works. Thanks!