Help! My Rhode Island Red is not eating nor very active.

She's been like this 3 days now. Her stomach looks very full all the time even in the morning. When I bring treats, all the other ones would run over but her. She is not very active like her normal self. She looks like she puff her feathers a little as if she is cold. Can they eat too much and bust their stomach? I'm attaching some photos here. Hope somebody knows the reason and can tell me what to do. Thanks tons!

The photos are not showing. I'm not sure why. When I tried to attach it, it says "you don't have permission to attach photos.". Guess I'm new?

 

I'm not sure. This is my very first flock. I raised them from babies since end of May and they are laying eggs nicely. Haven't had a broody one yet so no experience.