Chronic Sinus Infections are making me CRAZY!?

I just had my third baby 5 months ago. The whole time I was pregnant with her, I had chronic sinus infections. I think I had one every 6 weeks or so. I'd get a cold or be exposed to something (I have no idea what!), and then I'd get stuffed up and in a about a week I'd have a raging infection. I've taken so many antibiotics that I've actually become immune to some of them. Since I had my baby I've had 3 more sinus infections, and I'm battleing one right now. I'm FRUSTRATED! I've had allergy tests--no allergies. Asthma tests--no asthma. Blood tests--nothing shows up. I even had an HIV test, out of sheer desperation--negative! I've tried every at home remedy I can think of. I'm fresh out of ideas. My head throbs, my nose runs, and I'm sick of coughing. Docs don't seem to think this is a big deal. Anyone have any thoughts/ideas on what I can do to feel better? *Serious replies only PLEASE!*