cold and cortison

[bluegardenia]

after nine days situation worsened.on saturday i went to th doctor, he said ok to cortison for 4 days and then half dose, no areosol, but wash nose with saline solution and steam baths.he said to stop nac because it will cause more mucous. i felt better for one day and since this morning mucous augmented and is more and more thick. its not yellow, i dont have fever but i never had this in  my life. at this point im afraid its sinusitis, im afraid ill have to take antibiotics because of my allergies. ill go back to doctor tomorrow.
how did you have a diagnosis of sinusitis?n and what did you do? thanks
it means that every cold ill have sinusitis?? i wash my nose all the time!!