It is possible that over-activity has aggravated your mother's condition, either from the stent or completely unrelated and she hurt or strained other back muscles. Rarely, the stent can migrate out of place and cause pain. A simple x-ray of the abdomen would confirm that the stent is in the correct position and then there is little to worry about regarding the stent.
my friend has had a stent in her kidney, and ever since then she complains of her bones aching and she stays cold. Has anyone complained of these symptoms before, could they be side effects of the stent