Brief Answer:
Most likely due to allergy

Detailed Answer:
Hello

Thanks for choosing this platform

Recurrent nasal discharge us common in allergic rhinitis.Here giving anti allergic like chlorpheniramine with decongestant like pseudo ephedrine combination helps.Also nasal decongestant drops may be needed.Small amount of blood can be there due to minor trauma.
I won't get worried if bleeding was not severe and if it has stopped now.
I would request you to consult an ENT specialist for clinical examination and also for long term treatment if needed any.

Regards

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Brief Answer:
Avoidance of allergens is the best preventive measure

Detailed Answer:
Thanks for follow up

In view of positive family history the suspicion gets strong regarding the diagnosis of allergic rhinitis.
Here avoidance of allergens like dust,smoke,pets,insects or other suspected food items is the most important preventive measure.
Giving combination of anti allergic like cetrizine with long acting agent which prevents recurrence like montelukast for long duration helps.
Some of these children are prone to develop allergic skin disease or airway problem later on.
You may get him investigated for serum IgE level which is raised in allergic condition to get a clue to the diagnosis.
Nothing special is needed to increase the immunity as this is not a state of immunodeficiency.

I hope this helps.
Please let me know if you have any more doubt.
Regards

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