Hello dear,
The symptoms as mentioned in your post can be attributed to musculo-skeletal injury. X ray of the lower back will be helpful in detecting any
bone fracture.
The swelling is caused due to accumulation of fluid and blood (haematoma) following the impact.
Symptomatic relief can be obtained by
heat therapy, application of analgesic &
muscle relaxant gel, intake of analgesics like Diclofenac +
Serratiopeptidase preparations (to be taken after food) +
Pantoprazole (to be taken 30 minutes before meals).
Supplements of Calcium & Vitamin D can be included in his diet which will help in strengthening of bones.
If symptoms still persist, kindly consult an Orthopedician for proper clinical examination.
Till then, he should maintain adequate hydration & nutrition status, take proper rest and avoid stress.
Wishing him a Good Health.
Take care.