Hi, I understand your concern. After a myocardial infarction doctors would have used medications like Asprin, Clopidogrel [antiplatelet] and Streptokinase, Urokinase [thrombolytic] in post myocardial infarction management. All these medications can cause bleeding from various part of body. Colon is one such part. You must immediately inform your mothers attending doctors as this need immediate discontinuation of some drugs. And possibility of colonic cancer is of rare possibility here. You should reassure her with regards to this and may need investigation later if symptoms persist. Hope this answer was useful. Thank you.