Very hard to diagnose problems with nems. Sounds as though everything is okay as far as water parameters. Mine have closed up before and then split. Maybe yours will split and then you will have two. Sometimes there is nothing you can do that's just how it works. Sorry
Cipro, is the antibiotic. Unfortunately it looks like a hard road up hill for the anemone now. I have heard of this happening after they eat larger fish/tank inhabitants.