Well eventually after 2 xrays and 1 scan and 5 days of laxatives, my girl was operated on , an explorative procedure, they found that her colon had been cut off completely by a string of body fat wrapped around, it looked like a sausage, with nothing getting through, no doubt as I said at the time the laxatives wouldnt have helped, no wonder she was in pain, glad I insisted on the operation. She got through it ok(she is 13) and apparently there was no problem or damage to the colon, but the vet said he had never seen anything like it. Probably a good job she wet off her food as I dread to think what would have happened.