Hello I share your concern. A small lump in butthole might be related to external hemorroids, infected anal gland, anal tag. Possibility of cancer in your case seems to be very unlikely, so you shouldn t think about this. You should consult a general surgeon or gastrosurgeon for physical examination, proctoscopy or colonoscopy to diagnose the condition exactly. whenever it hurts I would advise you to apply lignocaine ointment to be applied locally. Sitz bath twice daily will definitely help. Hope this answers your question please feel free to ask for follow up question I will gladly answer you. Best wishes