Thanks to both of you for your comments, have you ever gotten pain in your lungs from the cold air? I haven't been coughing or wheezing, and I really don't think it was my heart

I do need to get my rescue inhaler refilled, there isn't much left so that might be part of what was happening as well. I've been avoiding windy conditions since it got cold, so that may well be the main problem as I've ridden in colder temps (well, not much colder) without a problem.