Hi thanks for your question.
Fatigue could be due to decrease in haemoglobin due to loss of blood from anus.There are few common causes of bleeding through anus.Haemorrides are most common cause ,followed by anal fissure
,rectal polyp,solitary rectal ulcer,proctitis,ulcerative colitis
and finally cancer of rectum.I would suggest you to consult a general surgeon
who may examine you and may perform proctoscopy/sigmoidoscopy
on you to determine cause of bleeding through anus.
Hope this answers your question.