Yes, if you have inflammation of lower gut, rectum and anus then strenuous exercise can cause bleeding. This is also possible due to Crohn's disease resurfacing. Since there is blood which you can see, it is coming from the lower gut. The possible causes are hemorrhoids, rectal polyps, colon polyps, diverticulosis (outpouchings from the bowel wall), inflammatory bowel disease (IBS, Crohn's, Celiac, ulceative colitis), or dysentery. Hence all these causes need to be ruled out. . You will need to consult your gastroenterologist again. Hope this helps. Take care!
or hemeroids??? thats possible too!