Hi SJSmall -
I know it can heartbreaking to watch the pets we love get older and develop problems. I admire you for hanging in there with this problem.
If she is unaware that she is pooping and has no control, then this is probably a neurological problem. This is probably a result of the stenosis that you mention. The nerves of the spinal cord that control this function are damaged as a result of this stenosis. Unfortunately there really is no medical treatment for this. Although it is possible that surgery could relieve the pressure on the nerves, whether this would be successful would just depend on how much damage to the nerves has already occurred. Obviously, this would be a major spinal surgery and most people are not interested in pursuing this in this age of a pet, but if this is something you are interested in, ask your vet for a referral to a neurologist.
Some dogs will do better with certain consistency of stools, so you could try different diets to see if this makes any difference. This is pretty much a trial and error situation, there is no one diet that works best in these dogs, it is just an individual thing. Sometimes diet doesn't make much difference though.
Getting her outside more frequently could also be helpful. She will probably still have some accidents, but it may help decrease the frequency of her messing in the house.
They do make doggie diapers that may help you manage this problem. Here is a website where you can check these out in case you interested. Obviously doesn't prevent her from pooping, but at least keeps it from making a mess.
I hope this information is helpful. If so, please click Accept. If you need additional information, please let me know.