Peasized Lump inside Rectum

Greetings,
I'm a 23year old Male and recently I noticed a strange very firm lump inside my rectum.

It's located at the front, about 2 inches inside I guess. At first I thought this may be my prostate, but upon applying pressure I didn't really feel anything, no uncomfort or anything related, however I ache for awhile afterwards if I was too "rough" examining it.

It seems to be behind the skin, so I thought it might be muscle.. It varies in size from pea-sized to swollen (quite large sometimes) and shifts about alittle when I apply pressure, it is -very- hard, not squishy at all..

Obviously the concern here is it might possibly be Cancer.

I have not passed blood and my stool seems fine, the only problem for detecting other things is I often give myself enema's (a life choice) so wouldn't really be able to tell (e.g. thin stool etc), Ive been doing them for years now (Which is another question, are there negative side effects to this?) and haven't really had any trouble outside of getting trapped wind every now and again and finding it difficult to pass wind afterwards (muscles inside lock up).

I'm very sorry for sharing probably "too much" information so excuse me, but I felt it best to share all so I can get some realistic feedback.
Thank you for your help and time.

[Dr. Kokil Mathur]

Hi!
It is difficult to diagnose a lump in rectum or anal canal without examining it through a proctoscope (a small instrument) or a colonoscopy. However, overuse and self-administration of enema can cause injury and infection which can result in swollen lymph nodes. The other possibility is a hemorrhoid or piles. This is common in individuals who are constipated and in those who use enemas. Other possibilities are a benign rectal tumor, a rectal polyp, a rectal abscess, genital wart or a hematoma. You will need a clinical examination followed by probably a STD panel or excision biopsy. Please consult your doctor for confirmed diagnosis. Take care!