I have a very sensitive lump beside my anus. it's not inside my anus. and it's not protruding from it. seems like the size if a pea. hurts to touch.

Perianal abscess: Or a deep boil is commonly due to accumulation of pus from a bacterial infection. It can present as a pea sized lump near the anus and is usually tender to the touch. They may resolve spontaneously. Warm compress & sitz baths may help. A simple doctor performed incision & drainage is often needed, a fast & effective treatment. Deeper infections & other conditions are possible in this area.