On going problems after surgery

I was wondering if anyone had any advice for me. I got chronic sinusitis in June of 2008. Because I live in Canada, the medical system works; but it works slowly. Thus it took 9 months before I was diagnosed with that, and then another 9 months before I had surgery (endoscopic sinus surgery) in January 2010, and I think it went well. I went from sleeping 11 hours a night, and complete 100 % exhaustion, to sleeping 9 hours a night, and able to have a life. However the problem is I still have some exhaustion, and am coughing up fluid (clear) in a light spray. This fluid can happen as much as 100 times in a 3 hour period (mainly mornings). The last 2 times I have seen my surgeon (early August and in May), they have had an endoscopy up my nose. There is no signs of blockage, or polyps but there is some mucus (not a great deal however). Thus my question, is why am I still coughing up this fluid, and have some exhaustion? I do not thing the answer is anything that has gone wrong with the surgery, and/or continued blockage of the sinuses. But am thinking that maybe I am allergy to something, causing this fluid to come out. But I had an extensive allergy test in January of 2009, and I tested negative to anything. Now I am just at wits end. Any answers will be appreciated. Cheers