Thanks for providing more information.
As you have itching and burning sensation along with moist anus so potential differential diagnosis may include fungal infection,Anal fissure,fistula,hemorrhoids,pinworm infection.
As you are suffering for a month so it is good's idea to consult your regular doctor or proctologist for a clinical examination.
A physical evaluation along with few investigations like blood and stool analysis/ colonoscopy will give you proper diagnosis.
Till then - have balanced diet, adequate fluids/ avoid alcohol, smoking, spicy food or caffeine.
Keep the region clean.
You can try OTC Prep H cream on anus.
Try warm sitz bath.
If itching is severe then take OTC Cetrizine.
Hope this helps.
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