Is it constant in size or receed back few hours after stool...let me know pain remains few hours after stool or only feel during stool...are you usually constipated....or any recent history of hard stool....if the pea sized lump come and receed back with passage of stool and bleeding P/R only during stool and pain higher in intensity during stool it may be Haemorrhoids....if pain comes after passage of stool and remains higher upto 1-2hours with recent History of Hard stool it may be anal fissure... the case should diagnosed properly with exact case history and examination of the part...