Re: Strange behaviour, vague "symptoms", LOTS of info
First, I'd start by changing her wheel. Get a nice bucket style wheel. While I do have and have used the plastic mesh spool wheel, the metal mesh ones have been known to catch toenails, and if she caught one, she may be reluctant to try to run on the wheel again.
What size is that wheel? I'm wondering if since she has grown up if the wheel may be a bit small in diameter which could cause her to feel uncomfortable when running for very long.
Do you have a snuggle bag that she can sleep in? That cage has a metal pan and you are using substrate bedding. If she is burrowing down into her substrate under her house, the metal of the pan could be causing the oddness in being hot/cold.