Hi. Have you seen pin worms in your stool. Anal itching can be due to many problems like intestinal infection and local infection, fissure in ano
and so on . It is better to get the area examined by a Surgeon to get the right diagnosis. It is difficult to get repeated pin worm infections unless you have grown nails , do not clean hands with soap or have a hutments/ dirty area nearby . Now-a-days there is combination of ivermectin
or try mebendazole
if you have repeated pin-worm infestations and carry on healthy tips I mentioned.