Help, my wild yeast no longer rising?
This is my first post here. I'm at a loss as to what has happened, but my firm wild yeast starter (1:1:2, starter:water:flour) is no longer rising when I feed it? I learned to bake with my mother as a child and, when I left home, she gave me a small piece of her starter. I've been baking sourdough on my own with it for 3 years and it has always just worked. I bake 2x a week and store the starter in the fridge or a cool balcony between bakes. I used to feed it 12 hrs before I bake and it used to rise to double its volume in 8-12 hrs depending on temperature. At present, I'm trying to revive it with daily feedings of bottled spring water and organic stone-ground flower (it's being kept at 78-79F). Ordinarily, I just use all-purpose flour and tap water but I'm getting desperate! I can see bubbles in the bottom of the glass jar but the rise is very slow and less than 25% in volume after 24 hrs. The smell seems to be less fruity (more sour) and it tastes more acidic than it used to. I've gone to the library and read a few books but I'm running out of ideas. It has been 2 weeks of feedings with no real change. Does anyone have any advise for promoting what is left of my yeast to grow? Sadly, my mom has dementia so my #1 resource can no longer offer me much help.