Rock flower anemone help needed!

[Wernerdin]

Hello everyone!

I'm having trouble with one of my 3 rock flower anemones.
Weirdly, the other two are doing perfectly. They are close to each other, so they are in almost identical flow and light conditions. I ordered the problematic one from abroad whereas the other ones I got from Lfs. When I received it like two months ago, it was beautiful, big, open and colourful but it started to degrade after some time.
I tried feeding it today and it reacted to the food but I don't know if it actually ate.
What could be the problem with it?
Thank you for the answers!

Here are some pictures about them:

 

[Gumbies R Us]

Did you have issues with it when you first got it? What about anything bothering it?

 

[Wernerdin]

Did you have issues with it when you first got it? What about anything bothering it?

Had no issues when I got it, it was bigger than the other two and looked good, altough it didn't really want to eat and as I remember it had a bigger mouth than normal too.
The only thing that could bother it is the cleaner shrimp, maybe.