A lot of times antibiotics don't work, didn't work for me for 5 years. The reason is because a sinus infection is different than any other sort of infection in the body. Here is the model of sinus infections and the best treatment
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, or perhaps a plastic basin or tub, with the shower running for steam.
Sinus problems are actually a medical frontier, so don't expect definitive answers.. You should go to an ENT and see if you have a deviated septum and get it fixed if possible, so you don't get reoccuring problems.