4wk old duckling eye issue

[Jenifervallene]

Hi everyone, I have a 4wk old cayuga duckling that has a pimple looking thing on her eyelid. There was nothing yesterday, she's not acting any different. It moves with her eyelid when she blinks. Shes in with 6 others all the same age and none of the others have it. Yes she has access to water to clean herself. Should I remove her from her sister's until I know what it is? Thanks so much for any input!