Hi thanks for asking question. You have infection with serratia which now a days acquired resistence against many antibiotic. So for this infection it better to use ceftazidime drug which is still sensitive in killing serratia.Usually combination drug needed like ceftazidime plus aminoglycoside like gentamycine. If nasal congestion is present take steam inhalation done along with use of antihistaminic drug. Mostly with this antibiotic you will get relief from serratia infection. Meanwhile maintain good health with fruits and green leafy vegetables. Drink more water.For fever relief paracetamol can be taken. I hope my suggestion will help you. If still no benifit then paranasal sinus x ray taken to rule out chronic sinusitis.