Brian, I recently had a 3 mm stone. It was sore for about a week after. You definitely need an ultrasound to make sure there's no more blockage. You can work with the urologist on the price if you dont have good insurance (like I did) , but you can lose your kidney if it's still blocked. Don't let this panic you, but you definitely want to call the urologist for a follow up.
If you went to the ER, how many stones did they tell you that they saw in the cat scan that you had TOTAL?. I notice that you said they found 3 X 3 stones (plural), indicating more than one 3 X 3 stone. Am I correct in assuming that from what you wrote? If you had more than one stone, then yes, it's very possible that you could continue to have pain and discomfort until all the stones you have completely pass. If you only had one stone, slight discomfort after passing it is possible, but that discomfort should not last very long. 3 mm stones normally do not cause me any discomfort after they pass. It's usually the ones bigger than 3 mm that cause me what I call "aftershocks", or discomfort for a little while after I pass a stone. That discomfort certainly doesn't last more than one day either and is very off and on and not steady discomfort. Hope this helps and please let us know how you are doing.