Hello Dr. I Have Been Having Some Discomfort In My

Hello Dr. I have been having some discomfort in my anal, I even thought the discomfort was because of G-string panties , I stopped wearing them three days ago, I took a mirror to check as to what could be the problem , I found a pimple right inside the anal, it was not painful and I am afraid, can you please explain to me what caused the pimple there and how can I treat it , should I be afraid like I am, does it need medical attention or it will go away in time.