There are two issues-- at least two issues. You are focusing on the issue of whether renal calculi cause pain in the kidneys-- yes, they can-- but your docs MIGHT be concerned about a different issue-- such as seeking pain relief for that problem in the ER-- which in many cases is NOT appropriate. It is not appropriate for a patient who is getting pain relief from one doc to seek out narcotics from the emergency room or another doctor. That type of behavior is actually against the law in some states (Florida has a law against 'doctor shopping', for example) and at the very least will get you discharged from the practice of many doctors. If your primary care doc or urologist is working with you, and gives you a certain amount of pain medication, it is not appropriate for you to go and get more pain medication from an ER. I can hear someone asking, 'but what if the pain medication from the urologist or primary doc isn't enough?' The answer is, then find a different primary care doc, or start listening to the things that you don't want to hear-- that you need surgery to remove the kidney stones, for example. OR that narcotics are just not the proper way to treat chronic pain from kidney stones.
The bottom line-- if a person keeps going to the ER to get pain meds, at some point things will go very bad. The patient will end up with untreatable pain, and in need of detox. The docs in the ER HATE to give out narcotics-- not because they are sadists, but because they know that doing so will destroy the patient in the long run, and they don't want to be part of that.
I recommend having a procedure called 'lithotripsy', and/or a 'percutaneous nephrostomy'-- which is a tube inserted into the kidney under x-ray guidance, allowing the stones to be removed from the kidney.