Thank you for your query. Would you please clarify a few things for me? 1) how old are you? Are you male or female? 2) do you have any urinary symptoms? like pain or burning sensation or increased frequency? 3)have you had any abdominal surgeries? 4)did the watery stools start after you were started on penicillin? 5) do you have any prostate enlargement (male) or uterine enlargement/ fibroid (female) 6) describe your pain. Is it only when you use the restroom or all throughout the day? Is it under you belly button? Or on your waist sides or on your back. Describe the frequency and duration. Is it like a cramp? Cystitis (urinary bladder) infection, prostate /uterus pathology (bulky prostate or bladder, urolithiasis (stones in the urinary tract) are some of the problems that can cause your symptoms Penicillin can cause loose stools. I recommend you see your physician right away. You seem to have pain in spite of taking pain killers. You will need some blood work, a urine test and culture. If male, then a prostate exam and if female a thorough pelvic exam. Drink plenty of water and keep hydrated. After you have consulted your doctor and made sure everything is OK, ask for a probiotic to help you with the loose stools associated with penicillin. Hope I ve been helpful. Please let us know if you have any further questions. Wish you good health