I recently have had hard pellet like stools and after moving my bowels i had gone back to work. I got very itchy in the anal area and went to wipe again and there was light pink blood on the toilet paper none in toilet water. I recently wen to my doctor and he did a test where he inserted his finger and removed some stool and tested it for blood it was negative i havent had it again but have had it 2 other times in the past what could this be??