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.
It sounds like he needs to go to the vet to be examined. Dependent on his age and other health issues he may need blood work, x-rays and/or have his urine checked.
Good Luck
Dr D