The most common and avoidable cause of bleeding during stools in your age group is Ischemic Colitis, the most common cause of which being over enthusiastic Blood Pressure medication. But this one is relatively painless. Piles or Hemorrhoids bleeding usually is accompanied by severe pain in the Anal region and usually there s a mass of flesh or more specifically, veins protruding out. It is also predisposed by constipation and overuse of opiates. There has to be an exclusion of an infectious cause- an amoebic or bacillary dysentery. Why don t you try a course of Ciprofloxacin 500 mg twice a day and Flagyl 500 mg twice a day for 5 days. It will do any good only. Only thing to be ruled out beforehand is Ciprofloxacin or any -floxacin suffixed dug allergy that you will know if you aleady have the knowledge about it or if you have developed hives after taking Bactrim DS or Sptran DS or any -floxacin drug type.