Nasal sprays and saline rinses are often ineffective against your problem, because the infection usually lodges in the upper sinuses, and you can't defeat gravity. The technique I developed actually uses gravity to get saline where it can be effective. I would suggest not using vinegar or any other additive, as it can mess up the balance of the good bacteria needed for proper sinus function.
http://www.medhelp.org/user_journals/show/2322
The Flip-Turn Sinus Flush is mildly risky, because you have to bend over to do it, preferably in a shower, but you can also do it outside on soft ground, or you can kneel down and lean over a bathtub with the shower running.
I still get sick too, once school starts, but it no longer turns chronic. At some time, you may wish to visit an ENT to see if there is a physical anomaly in your sinuses, if your problem continues to be chronic.