Hello I Am A27 Year Old Man. I Have Been

Hello I am a27 year old man. I have been a truck driver for about 10 years so I have hemorrhoids that flare up every so often, but just the past couple of days it has hurt quite a bit to sit or touch my buttocks. I was also sick with diarrhea for a couple of days this past week. Today I noticed a hard lump inside the innermost part of my butt cheek, it is not visible you can only feel it. Do you happen to know what could have caused this lump? And also is this cause for worry?