Riding usually causes the pain to flare up after about 45 minutes. Jogging for 20 minutes will cause it to swell up visibly about an hour later. The 2/week massage therapy I was prescribed for 3 months did nothing to help.
When riding, my lower back remains stiff, and horses tend to drift left when I ride. Mia is the horse I ride most of the time, and I think she has learned to ignore the extra pressure on her right side.