What Causes Blood Blister Like On The Outside Of Anus?

Hi,\


I have a hard peal like blood blister on the outside of my anus
Its very close to the actual hole and its very painful

Some times its very small other times it swells and becomes very uncomfortable

its very im barressing for me

My parntner has questioned what it is and im very worried now

Please advise me on what i need to do or what treatment i can take to get rid of it

I hope its not cancer or herpes