I had a kidney biopsy done 5 years ago. I was awake for the whole thing but they give you something to relax you and they numb your kidney so it doesn't hurt. You do have to lay flat on your back for 6 hours afterwards but it isn't bad. The next day I had some mild pain but nothing major. I would not be afraid to have another one done. I would rather have that done than a colonoscopy! Good luck and try not to worry, it isn't bad at all.
I have had 4 biopsies done. They are really not that bad at all! They gave me something to help me relax before and numbed the area. As the others have said you just feel pressure. It sounds scarier than it is. I'm the biopsy queen!!! I think I could do one myself! Try not to worry and don't put it off too long sometimes it can take a while for the results to come back. Judy