Glad you're feeling better! I think once you've eliminated any potential mechanical cause, it's very likely stress.
I think you'll find ways to cope and work through it ... some kind of "new normal." Perhaps it's an early reminder to take care of yourself even as you are trying to focus on taking care of Don.
We're here to listen, and whatever else you need, just let us know.
2014 Bobbin Bramble / Brooks B67
2008 Rodriguez Rainier Mirage / Terry Butterfly Tri Gel
2007 Dahon Speed Pro TT / Biologic Velvet