Hi there ~
I understand your concerns for your brother. The symptoms that you describe would be seen as vague in medical terminology. I believe that you brother may have a variant of sciatica
or a nerve root compression
at one of the lumbar or lumbosacral regions. He may also have an abscess
in the perineum
that is resulting in the numbness
and painful sensation and you might need to consult a doctor who can order tests after doing a physical examination. A neuropsychiatrist or a neurosurgeon would be the ideal person to take care of your situation. I hope this helps.
Take care and have a lovely day!