Hi welcome to Health care magic forum.
Thanks for choosing H.C.M.Forum.
Your brother of 50 years had been to hospital for
endoscopy, (it is not clear whether gastroscopy, urithroscopy,
colonoscopy, or some thing else. )
If it is urithroscopy, or ureteroscopy can cause infection, if it is others on possibility of infection to
kidney. If it is perforation the scene will be different, there will be
shock etc.
I advise you to consult a surgeon for diagnosis and treatment.
Pain in the lower abdomen suggests
urinary tract infection, stone in the urinary urinary tract,
prostatitis, descending colon infection, etc.
Wishing for a quick and complete recovery.
Best regards.