A.C.
My daughter had similar issues. The doctor said the problem is that it is self-perpetuating; if she is holding it in, her rectum gets stretched, and then she naturally goes longer between bowel movements. My doctor prescribed a laxative; there are several over-the counter ones, or you can ask your doctor. Of course, then you need to watch carefully, but it may make it easier for her, until you can get her back into an easier routine.