constipation in hen?????

Our Little Red Hen, who is about 7 years old and very small for a banty, has had trouble passing eggs in the past and required vet assistance for eggs too big for her. She is acting very 'frumpy' and acts like she wants to pass something, standing and pushing, but I do not feel an egg (I will keep checking). I'm wondering if she could be constipated, she is a wormaholic and this time of year likely eats too many worms. I have made her drink water and have her in the house for observation, but wondering if anyone has given any home/herbal remedies to a hen to treat constipation?

thanks for any suggestions.