hey-
i spent years working in the mattress industry (hah if people think used car salesman are scammers....you wouldnt believe the bedding industry..but i digress), and this is an incredibly common complaint.
a mattress DOUBLES in weight every 10 years from dust mite droppings. yeah, thats right. DOUBLES. seriously. guess what-pillows follow the same principle.
up until I started working in that industry, i kept my pillows until, well..shit i dont think i ever even bought/threw out pillows. good pillows are supposed to be thrown out every....(drum roll) 3-6 months. GREAT pillows (i.e. high quality latex/memory foam-and not shit generic memory foam-TP quality or higher/etc) maybe a year or two....or three.
change your pillow. most people find that when they do, they wake up with much clearer sinuses. you are essentially burying your head in dust mites every night, over and over, night after night....over time (and the longer you sleep/have your head on the pillow)-the worse its gonna be.
fuck dude you dont have to spend 500 bucks on a pillow, but go to wal-mart pay 10 dollars and see if it helps. if it does, buy a decent pillow, and a dust-mite proof barrier to keep the thing clean.
meh, thats my two cents.