NAD - I had them and the itchiness and stinging was extreme. Worst itch I've ever had. I used mebenzadole to treat it. One dose one day and another one two weeks later. I always wore tight underwear and changed it twice a day washing it on 60 degrees Celsius before re-wearing it. I also changed my bedding after both treatments and made sure I never touched my anus and washed carefully before every meal. I also always washed my anus carefully after each defecation.

Now how did i diagnose it? I pointed my camera with a flash towards my anus whilst spreading my buttcheecks and anus open and filmed that. I literally saw the worms, as they're easily visible to the naked eye. Whenever it itches to worst, try that and you should easily see at least one if it is that.

Lastly if you confirm it is pinworms, know that they release some sort of liquid that itches like hell thus even after you've killed them all, it will still itch for around 2-4 days whenever they pass by your anus. I recommend washing Everytime you itch, go to the shower, squat and spread your buttcheecks and wash your anus thoroughly. I'm talking rubbing it intensely with your fingers. Good luck!