I have an anal fissure, which is excrutiatingly painful. Even urinating hurts as the urine burns the swollen anal tissue. I woke up 3 times last night feeling a terrible need to urinate, but nothing came out. I suffer from bladder and Urinary Tract infections somewhat regularly, but I've been on amoxycillin since Thursday night, 3 times a day... shouldn't the antibiotic have prevented the infection? If I take cranberry pills for it, am I going to have to worry about constipation?