Cold air is often dry air. When you breathe in dry, cold air through your nose, your nasal passages react by producing excess mucus to humidify and warm the air before it reaches your lungs. This increase in mucus can congest the nasal opening of the Eustachian tube, essentially "gluing" it shut.
If the "cold" is triggering the swelling, break the cycle. Wear a fleece headband or beanie that covers the entire ear. Keep the ear cartilage warm for 30 minutes and see if the plugging follows suit.