i think they are yeast threads. they are mucousy white shreds of yeast. i pass the same thing. usually up to an inch long for me. they yeast only has two ways to come out really, through urine and bowel movements. oh and i guess if it is attacking your sinuses you could probably blow it out of your nose. we can also sweat out the toxins.
don't worry...the first time i saw them in my pee i was really freaked out. but a lot of people get them. i thought about getting it analyzed from a urologist for confirmation but don't really care to deal with any more doctors on this issue.