Hi,a nose piercing can't cause prolonged congestion problems in the nose.
Your daughter might be suffering from following possibilities:
1.)
Nasal allergy because of which she might be suffering from cold and
nasal congestion.In such a case she might also be suffering from nasal
sneezing,itching,watery nasal discharge,etc.
She might find relief by taking Antihistaminic(like Levocetrizine),Nasal
Steroid spray(like
mometasone),Nasal decongestant Drops(not to be used more than 10 days continuously,as usage for more than 10 days might cause rebound congestion in nose) and Saline nasal drops.
Avoidance of known Allergens is necessary.Also do steam inhalation.
2.)Adenoid enlargement.
Adenoid is a lymphoid tissue (like tonsil) behind the nose.It might get enlarged in a case of Allergy or infection.It can be diagnosed by Xray Posterior nasal space or nasal
endoscopy by an
ENT Specialist.In such a case your daughter might suffer from perpetual cold and nasal congestion.Snoring(ringing of nose), Mouth breathing(more during night),reduced hearing,reduced growth, might also occur.
In such a case she might find relief by Antibiotics,Antihistaminic,oral and nasal decongestants,Nasal Steroid Spray.
Even after the above measures, the the Adenoid size does not reduce,then she might have to undergo a surgery for Adenoid removal.
It would be advisable to consult an ENT Specialist doctor.He/She would diagnose your daughter's condition after doing nasal Endoscopy.
Hope this answers your question.Take care.