After 6 mths of what i've been told is "allergic rhinitis", no meds have worked. given oral prednisolone for 1 wk and no change. incorrect diagnosis?

Probably: There are other causes for a stuffy nose. The first thing I need to know is whether you have a septal deviation or sinus infection which would render the usual medications ineffective. If your nasal congestion cannot be relieved by topical nasal decongestant spray, you may need to have ultrasound or laser reduction of the turbinates- just make sure that the reduction is not excessive.