Need advice ASAP!!

It's been at least 3 days since my little girl Daisy stopped eating, she was fine eating and playing with the others, and one morning she just stopped eating. She is a 12 week old pekin. She has lost weight and I can't get her to eat anything. No treats. Or crumble, I've even tried adding water. She drinks just fine, I've been giving her molasses in water or electrolytes. She drank both, but still will not eat. Other than the not eating, she swims, preens, and walks around. It hasn't been overly hot and all 3 of my babies eat and play together and eat the same things. They get to forage daily, and she joins in, in the fun. I was watching to see if she would eat then, but everything she picked up she spit out. She still try's to eat mud :/, so I put come crumbles around the run , she pecks at them but again spits it out. I'm so worried about her. I've checked her bill inside and out everything looks good, checked her gullet and it's empty. Her poop is 98% water so I know she's not eating when I'm not looking. I really don't know what I can do. Any advice would be appreciated

Have you tried to scramble up an egg for her? Scrambled eggs will usually get any chicken to eat...for now just to get some nutrition into her.

I haven't tried an egg, I'll have to give it a try thank you

Update- tried a scrambled egg, she looked at it and walked away, I can't figure out what is wrong. Tried to separate her from the others with food to see if she's just scared or being bullied. She just cried and cried so I let her out. I'm getting desperate

Wondering if her mouth or throat are sore, I looked inside it all looked healthy. I'm so worried.

You could also try yogurt. Yous aid her poop is watery, no signs of blood? (Cocci)
Does her breathing sound normal (checking for respiratory issue)?
You said she is in with other chickens but the food wasnt touched, or you positive she isnt eating when your not there? From another feeder? Have you felt her crop to see if you can feel anything in there? She isnt acting sick or have any other symptoms?

No, I haven't seen any blood, she isn't having any trouble breathing either. If she's eating when I'm not there it isn't much at all, every poop is clear and all water. My other pekin and the runner mix have been with her since the day they hatched, and they have been everywhere together. She is the only one who isn't eating.
This is her, she has lost weight, but she still runs around and swims, it's very strange.
I got her to nibble on grass, still not very much. I've tried all her favorites but she just walked away from everything.

UPDATE I got Daisy to eat a little but of shredded chicken and kale, but I noticed she is having a hard time chewing/swallowing. Is there any problems that anyone knows of and treatments for a sore/injured mouth/throat.

Ideally, you can carefully look into her mouth (this is where I find our vet really helpful).

One person fairly recently found a bit of metal in the roof of her duck's mouth, I think it was.

I suppose gape worm may cause problems like this - again you need to find what it is in there.

A tablespoon of apple cider vinegar in half a gallon of drinking water might help a little. Or two or three drops of colloidal silver in the water, if you use that kind of thing.

Thank you, I'll try the vinegar if that doesn't help I'll contact a vet