I have that happen when I ride or hike in areas that have things I'm allergic to - like Ponderosa pines (which was a real pain when I lived in New Mexico!). Might be something in the air you can find only this time of year. Cold does not affect that me that. My nose runs, but I don't sneeze like that, and it stops as soon as I come home.

I find that Claritin helps when it's allergy related. If Benedryl helps, consider some kind of allergy meds. But man, it wiped me out! I was pretty miserable for about 24 hours.