if you've had three unsuccessful attempts, I agree that a scan is necessary to digits out exactly where it is. on e they can see it on the scan, a surgical attempt to remove it should be pretty easy. I understand that you are worried, but it shouldn't be much more than a small incision and lots of local anesthesia
to make sure you don't feel anything. I wouldn't try another attempt in the which sounds like it will just cause you more aggravation. so sorry that you have to go through all of this, but it sounds like it will be resolved soon. please let me know of you have any more questions, and good luck!