Hello! I have been through your question. Related your concern I think you should know that taking some antibiotics could change the normal flora of intestine leading in overgrow of clostridium difficile bacteria and cause the C.difficile infection that can range from mild to life-threatening. Symptoms of more severe C. diff infection include watery or bloody diarrhea (like you have), severe abdominal pain,loss of appetite and fever. Flagyl is the right medication for this infection but what I suggest further is take a lot of water or tea, use probiotics as well and do a full blood count (to evaluate HGB and RBC). I need to clarify better if the blood with bowel movement is red or black because if it is black you need to talk with a gastroenterologist and to do a fibrogastroscopy (to exclude an ulcer reactivation), just in case. I hope my answer help you. I wish you a quick recovery.