Hello Fatema ,
Welcome to Healthcare Magic forum.
Your history does seem to resemble that of allergic rhinitis
which is common in children especially if there is any family history of allergy or asthma or there is frequent exposure to dust, pets or birds, pollution etc.
I assume your pediatrician
has ruled out any infection and completed a course of antibiotics to treat if any.
is an appropriate prescription if the cause is confirmed to be allergy.The mouth breathing
is definitely due to nasal blockage and congestion which commonly occurs due to infection or allergy or an ENT problem like tonsils adenoids hypertrophy or deviated nasal septum
A complete Ear nose throat examination, chest auscultation and blood tests like complete blood counts and blood smear and erythrocyte sedimentation rate(esr) can mostly differentiate between them and give an exact diagnosis .
So it is advisable to discuss it with your doctor if they can be done and then treatment with singulair can be given if allergy is confirmed.
Meanwhile steam inhalations and warm salt water gargles thrice daily may provide relief if acceptable to her .
Also please avoid the possible allergens like dust, pets and smoke.
Wish her a speedy recovery.