If you put in a search at the top of the page for "sesame", you'll see alot of other people talking about the same thing for a type of Tapeworm egg. You can also find it described by veterinarians for detecting Tapeworm in dogs.
The white, string-like things, sound like parasite. It could be a couple of different types.
Look for stuff that floats too.
Are you taking something right now for hitting parasites?