Hi. Thanks for your query. Noted the history and understood the concerns. Since you have been given medicines for Urinary tract infection the most probable causes I can think for the fainting, stomach pains and diarrhea can be as follows: Antibiotic induced diarrhea. Secondary intestinal infection. Septicemia due to UTI or intestinal infection. I would advise you the following in such a situation: Hold on the medicines. Rush to ER for clinical evaluation, examination and investigations to get an appropriate diagnosis so that a proper management can be done and save further complications. Tests of blood, urine, stool their culture and sensitivity may help in a long run. Take probiotics and electrolyte solution with plenty of oral fluids.