Where are you located (state/country)?
What do you feed?
Photos of your pullet and her poop would be helpful.
I agree with
@casportpony most of the time a crop problem is a
symptom so figuring out the cause is always a good idea.
Is she lethargic?
I would start out by doing something basic like caging her for a couple of days. Put her on puppy pads so you can see her poop easily. Provide her with water. Give her 1 teaspoon coconut oil and massage the crop. Massage the crop gently several time more through out the day. I usually give another teaspoon coconut oil before roosting time. If she is complaining loudly, she can have a little wet soupy feed. No scratch, no seeds, no whole grains - nothing that really has to be processed.
See if the crop is empty in the morning.
If it's not, then re-evaluate. Hydration is very important, she should not be without water during waking hours.
If you can have a fecal float performed that would be a good idea.