Lumbar Spinal Stenosis: This condition is characterized by narrowing of the spinal canal, which can cause pain, numbness, or weakness in the lower back, legs, or buttocks, especially when standing or walking. The symptoms worsen with activities that extend the spine, such as standing, and improve with flexion, which could explain why the pain occurs after a golf swing but not during it.

Osteoarthritis of the Hip or Lumbar Spine: Wear and tear on the joints can cause pain, especially with weight-bearing activities or movements that involve the affected joint, like standing up after a golf swing.
Muscle Strain: Overuse or poor technique in golfing could lead to strain in the muscles of the lower back or hip, causing intermittent pain.
Trochanteric Bursitis: Inflammation of the bursa over the hip can cause pain on the outer aspect of the hip, which might be exacerbated by activities like golfing.

Cauda Equina Syndrome: A serious condition where the nerves in the spinal canal are compressed, leading to severe pain, numbness, and potentially bladder and bowel dysfunction. It requires immediate medical attention.
Abdominal Aortic Aneurysm: Although less common, severe back pain can be a symptom of an abdominal aortic aneurysm, especially if it is expanding or rupturing.
Metastatic Bone Disease: Cancer that has spread to the bones can cause pain, and given the patient's age, it's a possibility that should not be overlooked.

Paget's Disease of Bone: A condition that affects bone remodeling, leading to weakened bones and potential for deformities. It could cause localized pain and is more common in older adults.
Osteonecrosis of the Femoral Head: A condition where the blood supply to the head of the femur is interrupted, leading to bone death and potentially severe hip pain. It's less common but could be considered, especially if the patient has risk factors such as long-term steroid use.