"It has to be parasites !"

No, it doesn't.........My hunch is all your upper respiratory issues are associated with candida. Many Dr's think a majority of sinus infections are yeast, not bacterial.

I had my tonsils removed in the mid 90's to what the Dr's thought to be strep stones: in hindsight, I'm convinced they were candida stones from all the oral thrush pix I've since seen. In addition, chronic sinus issues are candida as well, constantly draining down candida laden phlegm down my throat and draining into my stomach. In fact, leading up to my Gi swelling which lead to being hospitalized in 2003 beginning my journey trying to deal with a mysterious digestive disorder, were months of cycles of abx trying to address a chronic sinus infection. The abxs contributed to what ptu me in the hospital. Also, I get many headaches, sometimes migraines with the visuals, other times acute sinus pains (hard to tell which is which sometimes). IMHO, my situation is all interconnected with Candida.

I have recently tried Colloidal Silver nasal spray and what came out turned from roundish, white as you describe to sticky to yellow and stringy. Not sure what that means but, it was notable enough to observe. I'm leery in going beyond the recommended 4 prays per day for no more than 10 days so, taking a few weeks off before using the CS spray again. Decongestant seems to help keeping the phlegm factory to a minimum, even if it's just using the vic inhalers thingys.

Keep seeking and you might find what I have come to believe is happening with my situation for much longer than even I can determine which goes back at least 2 decades, perhaps as far back as I can remember: childhood.