i think you should go to mcdonalds and have a cigarette!
i ran for a good part of my life up to 8 miles a day, was in great shape, didnt smoke, didnt drink, no drugs, hiked, did weight training and got PN anyway. Sometimes i think maybe i should have smoked and drank. You can definitely drive yourself crazy trying to figure out what caused your PN. Mrs. D has given you a good starting place and go from there depending on results. If the pain is affecting your life have it treated.