Might have pin worms...not sure.?

I have been noticing for almost a year white/yellowish strings in my bowl; however, they NEVER moves! Thus, I started ignoring it thinking it some kind of indigestible rice. Couple of months ago, I noticed that there's small but bit think strings smaller than 0.5 ( Approximately) and there's big strings around 1.4cm ( Approximately) - it's what I guessed. I feel normal. Nothing hurts. But sometimes, my butt hole itches and there's some white powdery stuff near my labia majora ( basically vagina skin) which sometimes itches too. Dunno whether this is related to having worms.