For the past year, every once in a while I have had a very strange sensation in my abdomen which is in the center of my belt line. It's really hard to explain but it feels as if I have to urinate, but not exactly like that. I feels kind of as if something is irritating the nerve that senses when I need to urinate, if that makes any sense. It comes and goes and sometimes it will last weeks between symptoms, but usually when it starts I will feel it off and on for at least 2 weeks straight. Nothing I do seems to set it off or make it feel better. I have been to the doctor and they did a urine sample three separate times and it seems to check out just fine, so they say it's not a urinary tract infection and there wasn't ever any blood in my urine. Can anyone shed any light on what might be happening? It can be very annoying and irritating.