I Have Developed A Lump The Size Of A Pea

I have developed a lump the size of a pea on my anus that has a black dot on it. I also notice a little bit of what could look like pus near the black dot. The entire lump is red and seems like a hemorrhoid but the black dot is concerning me. It's fairly small.. About the size of the tip of a pen. And it looks like there might be a little bit of puss but I don't think it's an abscess. Any idea what this might be? And how I should treat it? Thank you!