If you can't actually feel a break, and both of her legs are splayed out behind her, and she's pulsing her vent, I would agree there's a good chance she has an egg that has pressed/ or is pressing on the Obturator nerve. If you can't take her to a vet, my first line of action would be to move her inside, into an area that has plenty of traction as excessive splaying can be damaging as well.
I would also try to get some calcium in her. There are several calcium supplements you can use, such as, tums, calcium citrate, or what I have had the best luck with, Calcium Gluconate. The first two can be boughten at most health stores, and you'll be able to find the gluconate at most feeds stores like
TSC. If you have any NSAIDs, specifically, carprofen, ketoprofen, or meloxicam, you might be able to use that too.
Is she drinking? Would you mind posting a few pictures of her?