Hello from JustAnswer.
The first concern when there is significant pain around a ureteric stent that is worse with urination and walking would be an infection. It is also possible that there could be an obstruction of the stent.
Since you say that the pain is killing you, that would indicate a severe level of pain, so it would be better for you to be seen quickly, either at a hospital or an Urgent Care center or Walk-In Clinic.
If I can provide any additional information, please let me know.
It is possible that a kidney stone is obstructing the stent. They will typically insert a stent that is large enough to allow passage of the stones that are seen, but it is possible that the stones could not be completely seen and are larger than they appeared. However, we still would be concerned first about a possible infection.