There are many types of stones and there are some which are stubborn, called staghorn.
It might be possible that even though the stone is out but some of its remains are left behind, which are causing the pain or it might be just the affect of medicines. You can wait for few days and observe.
If the pain persist, go to your doctor and tell them.
Next Steps
Next step might be to go for X ray or other tests to see if the remains of the stone are not lodged somewhere else, along the line of ureter.
Health Tips
If you still feel pain, it is recommended you take a second opinion.