Hi, 2 Years Ago I Had About 12 Inches Of

Hi, 2 years ago I had about 12 inches of my bowel removed due to diverticulitis. I have had mild to moderate constipation since. I use a stool softener daily. Yesterday I had a bout of diarrhea and today I feel as though I need to have a bowel movement constantly. Then this after noon when I was cleansing myself I felt a lump on the right side of the anal opening. When I touched the area, it was very tender and hard. Please advise.
SM