Thanks for posting your query.
I am Dr.Ratnakar Kini and I am pleased to assist you.
There are many causes of sore anus like hemorrhoids, fissures, dermatitis
, candida infection and drinking beer, coffee etc. So in your case, it could be candida or drinking alcohol.
Only after examination of the anal area one can tell for sure what is causing it.
I hope that answers your question.