Thank you for your query. I can understand your concerns.
It seems you are having pruritus
ani and the probable cause is enterobiasis or thread worm infestation,as the peri-anal area looks otherwise normal as you have mentioned. You will get relief if you take deworming drug like tablet Albendazole
400 mg at bed-time today and to repeat 400 mg at bed-time after 10 days .
There are many other causes but the cause is not clear in many cases.
Use plain, non-coloured toilet tissue. Wipe your anus gently after passing faeces.
Have a bath or shower daily. If possible, wash your anus with water only.
If you use soap around your anus, rinse well.
Change your underwear daily.
After washing, dry around your anus properly by patting gently (rather than rubbing) with a soft towel.
Do not put on underwear until your anus is fully dry.
Wear loose cotton underwear (not nylon).
Keep your fingernails short to limit any damage done to the skin by scratching.
If it feels very itchy at bed-time take tablet Hydroxazine 25 mg at bed-time daily for few days.
Dr. T.K. Biswas M.D.