Starter didn't rise after last feeding
I've had a starter going for about 2 weeks now I think, and it had been fine so far. I didn't know that much about sourdough starters when I first made it, so I used the recipe from a baking book I have (which is equal parts water and flour with one packet of active dry yeast). I've been feeding it twice a day and pouring off at least half every 2 to 3 days.
A few days ago my starter stopped rising/bubbling as much after feeding it and I was a bit concerned, so I decided to stir in more flour so that it was a 2:1 ratio of flour to water. After doing so the starter slightly more than doubled in volume (to 8 cups) within about 2 hours and then gradually went back down to 4 cups over the next day. I tasted a bit of it to see if it was alright and it tasted like yeast, beer (just a little bit), and biscuit dough. The recipe I was going to use it for, was in the book I found the starter recipe in, so of ocurse it required a starter with equal parts flour and water (though I guess I could have used my starter the way it was and just slightly increased the amount of water and decreased the amount of flour in the bread recipe).
So today I mixed in enough water to bring it back to a 1:1 ratio of flour to water, added another cup of fresh flour/water mixture, stirred it up really well, and then pour out about half (since it was up to the top of the container and I didn't want to risk it overflowing). I did that about 4 hours ago now, and the smell, color, and consistency still seem alright, but I'm concerned because the starter hasn't risen or bubbled since then (except for small bubbles on the surface). Has it gone bad, or do I need to do something to revive it?
I've been using tap water and bleached white flour, and I'm keeping it in a 2 quart glass container with a towel on top.