It may be useful for you to question the label of "sinus problem."
A good clinician should be able to differentiate between acute, chronic or recurrent sinusitis, which may have a bearing on your medical.
In the last couple of years sometimes when I get a cold my sinuses become quite blocked for a couple of weeks
Some may suggest that this is within the range of what may be considered "normal," but there could be other key factors in the story which you tell of your symptoms, which may have a bearing on your medical. You should not fly if you are suffering from sinusitis. Good luck.