Acetone smell in well-fed starter
I've been working on my first sourdough starter for almost two weeks now (it'll be two weeks on Sunday). Things were going well initially, and around day 3 or 4 I started feeding it every 12 hours. It got that nice, tangy smell but never rose much at all. I just kept feeding it every 12 hours, waiting for it to start doubling, and two days ago it started to smell strongly of acetone. I know this is common, and from my searching it seems that it is usually a symptom of a hungry starter. I fed it as usual yesterday at 7:30 am, and called King Arthur Flour's baking hotline yesterday afternoon around 3 pm. They suggested to go ahead and feed as usual right then (dump all but 4 oz and feed with 4 oz of unbleached AP flour and 4 oz of spring water), and see if the smell went away by that evening.
It did not. I'm in central Texas and it is still quite warm here, so my kitchen gets up to 77 during the day, and we keep the a/c around 70 at night. I thought that maybe the warmth was causing the yeast to consume all the flour nutrients too quickly and that giving it a third feeding during the day would help, but it doesn't seem so. I then thought that maybe I could add a tablespoon or so of whole wheat flour to my usual AP flour (still keeping the total at 4 oz), in the hopes that it would help the yeast become active enough that I could start storing it in the fridge. I did this last night, and it did indeed rise a little more (maybe 50%), but it still smells like acetone.
Any suggestions? Should I just keep feeding as usual and wait it out? I'm happy to be patient and am in no hurry, but I'd just like to know if I need to do something in addition to my usual feedings to get this smell to go away.