I Am Suffering From Sinusitis Aftet A Cold About 1

I am suffering from sinusitis aftet a cold about 1 and half month i have headache pressure on septom and pain and like any kind allergy and i have a. Ct scan about 8 days ago but report is normal and doctor give me antibiotic for 5 days solvin cold nasal spray and inhaling capsules but i have no relief
What test give me accurate medicine for this
And it can also caused by any allergy
Then which test given for this
Please suggest me i am very sick from this disease