Thanks for putting up your query over here. Going through your questions,I recommend that you can continue taking mucinex and fluonase.Yes,you can take 1 extra tablet of mucinex with a gap of 12 hours after the first one.Besides,you need to have steam inhalation,keep yourself hydrated by drinking minimum 6-8 glass of water daily and avoiding smoking,alcohol,applying warm compresses around nose,avoiding cold drinks and fried foods,consuming fresh green vegetables and fruits for vitamin A.You can also opt for doing regular breathing exercises which will help you in long run. But if the symptoms worsen or are accompanied by fever,cough,redness of eyes,you need to visit a physician because in that case you may need an antibiotic course for 5-10 days. If your episodes of sinusitis are more often like for more than 4 weeks,causes of chronic sinusitis needs to be ruled out like asthma,hay fever,nasal polyps,deviated nasal septum etc.In that case,you will need to visit an ENT surgeon who may opt for nasal endoscopy if required. Also smoking and frequent exposure to pollutants (at home or at workplace) may increase the chances of chronic sinusitis. Hope I helped you till some extent with your query. Thanks and regards.