Can Too Many Depomedrol Shots Given For Allergic Sinusitis Aggrevate Cough?

I have been suffering from an allergic sinusitis for more than 20 years and it finally has been worse from 8 years ago with starting severe coughs every half an hour. It is actually back nasal drops which make me cough severely. I have been visited by many specialist and has undergone many tests including methacoline challenge which showed nothing. 3 years ago I got a shot of bethametazone which was recommended by one of my friend and the cough was gone for 2 years. but it started again since July. I got a shot of depomedrol which worked for 4 month and I had to take another shot again last week. It didn't work like the previous time but it's still better than nothing. My question is that what am I supposed to do if it starts again because I'm told that too many depomedrol shot may affect my health in long tile. or is it a good idea to undergo a surgery or not. This coughing is really making me miserable at work and also at home sometimes I really feel bad in the public because everyone thinks I have a flue and they stand away from me. thanks, Nilou