You most likely got it from golfing. I bet you're good at it too. ;-) But as I mentioned, it can lead to a repetative injury or you can have degenerative changes.
Yes, please follow the suggestions above and see how you do. If you do not improve, see your doctor. Keep us posted.
Thank you. Yes I do have a bit of lower back pain, but not all of the time. I will take your advice.
Do you have any back or hip pain? Any numbness or tingling going down your leg? Often times with golfer it is a repetative motion, so this might have caused some degenerative (wear and tear) changes to your back and pinched a nerve that goes down your leg (sciatica).
However due to your age, there could be other causes that warrant you to get this checked out by a doctor just to make sure it is not related to your heart. I highly doubt it is, but to be on the safe side you should have him check you out and have him check your back and legs as well.
In the meantime, hold off on the golf for a while, avoid prolonged sitting, do not slump when sitting, and you can continue your walks with your dog.
Let us know how you do. :-)