Bill, from your description, I believe the situation could present a risk of cascading failure of the foundation, increased damage to the building and a high risk of injury to workers. You should get a professional site assessment and place stabilization and safety at the top of the list of immediate concerns. You will need to understand the failure process to properly design a practical solution. Know the roles of water, mortar and stones, trees roots, soils, grade, surcharge(from the site, activities, future construction and equipment) and frozen walls, and so on, in the building system.
Take good care
