Thanks for query.
It is possible that there might be nasal congestion
giving rise to bleeding.
Put some nasal decongestant nasal drops like Otrivin or Nasivion
nasal drops in the nose.
Do not allow him to touch his nose frequently.
Give him vitamin C
Go for blood for bleeding time
and clotting time.
If any thing wrong in reports then consult your doctor.
Ok and bye.