Starter was growing, now it's not
I started my first starter 5 days ago with 1/2 cup hard well water and 1 cup old whole wheat flour. Discarded all but 1/2 cup starter and fed 1 cup old AP flour and 1/2 cup well water every 24 hours for day 2. Got some activity and rise during the first 48 hours. Day 3, went to twice daily feeding of same. This is when rising stopped. I have continued to feed every 12 hours for day 3, 4 & 5. Added some extra water because starter was very thick. No rise, though some bubbles. Day 5, I fed same in am, 12 hours later no rise or bubbles. I fed with whole wheat flour to try to give more yeast at evening feeding. Day 6, 12 hours later (this morning) no rise, no bubbles. See picture. My house is fairly cool (68F) for the most part. During the days of rise, I had a fire in the wood stove, and the house was warmer. I don't have an oven light, and the top of my refrigerator is not very warm, so I keep the starter in the kitchen on an inside wall in a central location.
What's going on? Should I go back to feeding every 24 hours to give it more time to rise? Should I feed whole wheat or AP flour? Is my flour too old? Is the extra water a problem? Is the well water a problem? Is my house too cool? Is altitude a factor (I'm at 9200 ft)? These are some of the things I have thought of that might be a problem.
I'm discouraged, as initially I got some activity and rise, and now, nothing. And I'm running out of flour, which is hard to come by in this Covid-19 world. Ditto for trying to buy filtered water right now, so I'm stuck with well water. When I run out of flour, do I just put the starter in the refrigerator to keep it dormant until I can feed it again?
I appreciate any insight you can give. How best to bring my starter back to life?