For the last few years, my sinus drip into the back of my throat. I let it go. I then become sluggish, extemely tired and find it hard to breathe. I go to my doctor and he checks my check and says there is nothing wrong and sends me on my way. About a day later I`m so light headed I cannot walk down the hall. Now I go to the doctor, tell him I have a sinus infection , he gives me anti biotics and it clears right up. I start bring up large amount of transparent flem. It use to only happen int eh winter, but I have it right now. ANy ideas?