Axolotl floating and not eating

[Madi01]

My axolotl has been floating for nearly two days now and can’t seem to get back to the bottom. Yesterday night she was not eating and was moving frantically up at the top of the water trying to open her mouth but struggling.

I have done a water test each day the first day nitrate was a little high so I did a water change it’s back to 0 now, and the temp in the tank iis at 20 deg Celsius which I am struggling to get down

I have no idea what’s wrong, please help!