If nasal allergies are a problem, some of the newer nasal sprays like beconase or flonse are a godsend. There are several things out which are mild enough to use even with children and have side effects which pretty much correlate with the problems you have without the spray.

Benadryl is awful -- turns you into an absolute toad. A squashed one at that.

Sudafed's okay once in a long while, but the longer you take it the more likely you are to have the heart flutter problem.

I have a friend who gets awful sinus problems, and when she really just can't stand it any more, she'll smoke a cigarette. It's the only time she ever smokes, but it does clear her head (and kill the sinus headache pressure) . She figures tobacco is a medicine and should be used like one.