It definitely looks sad today. The good news is that it is still attached and the mouth isn't gaping a lot. My guess would be that the system parameters are simply fluctuating too much. There really is nothing you can do about this other than letting the system continue to mature. your test results may not show it, but things like pH, alk and Ca, will be a bit all over the place for a while. Many things in a new tank will fluctuate constantly throughout the day. This is the main reason people say to wait at least 6 months before adding an anemone to a system, a year is even better. I can take this long for a tank to truly stabilize.
For now, I would just continue with the regular water changes and try not to make other changes, light lighting or flow, unless absolutely necessary. Hopefully the fluctuations are minor and the nem will be able to ride it out.