Just got back from the vet.
She thinks Mama is passing out, not a seizure
or stroke. She heard a heart murmur (which is new), and thinks she has high blood pressure, maybe kidney and thyroid issues. She's slightly dehydrated, which could mean something with her kidneys, as she gets lots of water and canned food.
She also noticed that her retinas are degenerating, and that her pupils aren't dilating nearly as much as they should (also new).