Try a neti pot. Basically it is a little thing like a miniature teapot that you fill with warm water mixed with saline. You put it in one nostril, tilt your head and wait till it pours out the other nostril. Then do it vice-versa. I know it sounds nasty, but it works. Google it. You can get one at CVS or Walgreens for 12 bucks and it comes with 30 saline packets.
I was dying after my trip to New Smyrna, the oak pollen was killing me. I tried all sorts of meds and nothing helped. A friend told me about this little gem and it worked great.