I saw a doctor Monday and he put me on macrodantin 50mg 4 times a day for pain in UTI only had pressure pain in pelvis and was going toilet a lot then. Within 24 hours I had no pain and started to go toilet less. Wednesday morning early hours I started getting an ache in my left side like a annoying toothache and also stabbing pains at times. I went back to doctor Wednesday evening he tested my urine said there was still a lot of bugs in it and upped the macrodantin to 100mg 4 times a day. I'm on the 100mg dose 24 hours now and had some pain free time today but this evening my left side is gnawing away at me terrible achy pain. It's only easing a bit now but still there. I thought the antibiotics would if been working by now as it's day four tomorrow between the 2 strengths. Any idea when it will kick in to rid me if pain?