Hi.. Thanks for the query.. Sinusitis can occur due to a number of causes like viral infection or cold and flu, allergies, dental infection and tooth extractions, deviated nasal septum etc.. So first of all you need to consult an Emergency room and get evaluated so that they can do a clinical examination and an X-ray of the sinuses to rule out the exact cause of sinusitis.. Once the cause is ruled out treatment can be planned accordingly.. For now you can take a course of antibiotics like Augmentin,anti inflammatory painkillers like Advil, use decongestant nasal sprays and do saline nasal irrigation.. If you are known allergic you can add levocetrizine for relief.. Hope this helps. Regards.