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The symptoms of nasal discharge is due to allergic rhinitis
and if it is chronic that is long standing then it may be due to sinusitis
for which you can get treated.The cough you are having can be due to chest infection;allergy cough.The stomach upset
you have may be having gastritis giving rise to nausea;and loss of appetite and since you are not having food properly that may be the reason of constipation
.Please consult a doctor and get treated if you want take medicine for acidity and the stomach complaints will reduce.