Can you do something for me? It will help us determine if this problem could be a stuck egg or just sour crop. You may want to slip on some latex gloves.
Place your hen on a counter or work bench. With a soft wet Kleenex, gently push on her vent. Look closely and feel through your fingers if she pushes against them with her vent as if she's trying to poop.
Try it one more time. Look and see if her vent tries to open up as if she's trying to lay an egg.
If her vent remains flacid as you pushed on it, more than likely she has sour crop and not a stuck egg.
Place your hen on a counter or work bench. With a soft wet Kleenex, gently push on her vent. Look closely and feel through your fingers if she pushes against them with her vent as if she's trying to poop.
Try it one more time. Look and see if her vent tries to open up as if she's trying to lay an egg.
If her vent remains flacid as you pushed on it, more than likely she has sour crop and not a stuck egg.