Nik...the very best gift I could ever give to one in your shoes is a "neti-pot". Find it, try it, LOVE it!!!
Its a tiny little teapot shaped thing with a long skinny spout. You mix saline solution - wam water and salt - in the teapot and pour it into your nostrils, one at a time. Look straight down into the sink, tilt your head to the side, insert the neti-pot spout into the top nostril and pour...the water will flow out the opposite nostril. Repeat on the other side. Then blow your nose. Repeat if your sinuses arent yet completely cleared out.
My hubby uses this everyday.... It's the best thing ever for someone with allergies esp. seasonal, and sinus.
Spring time in USA is really really bad for people with allergies. Ever since we saw the Neti pot - on Oprah - it's a blessing for him!!!