Work on a formal heel and reward for that specific behavior. Keep the leash short so she understands what you’re asking. In conjunction with this, I would stop dead every time she goes to the end of the lead. By continuing the walk, you’re rewarding the undesired behavior.
I am a BIG fan of tab leads for this.
This sounds like a potential blockage. Please get your dog to the vet NOW…DO NOT wait on this. Blockages and obstructions are usually fatal if not handled quickly.