When you say "used to", do you mean while growing up or by a Dom? With what instrument? Hand? Ruler? Crop? 6' cane? Pain is usually the body's way of saying "stop". The amount of pain generally indicates the potential for damage. (As in most things, your mileage may vary.) So what are the results? An abnormally shaped clit? A lack of sensation? An increase of sensation? Did it explode and never grow back? Is it now larger than your thumb with green warts all over it? (If so, please upload the pix.) A few details of the current situation might be helpful for a more accurate and specific answer!