I received this message from a woman who is worried about her piercing:
I got my industrial done back in November....my boyfriend and i were doing a little rough houses and i hit my ear with his knee and when i went in the bathroom to look my bottom hole on the back side was bleeding. The only time i bleed was when i got my piercing 4 months ago. What could this be, and what can i do to stop it???
That would be trauma, and it is definitely not good for healing piercings. Excess trauma can cause delayed healing (or re-healing), and possibly migration or other complications. It is very important that you are careful with your piercings!
You should care for it as though it is a fresh, healing piercing (which it is, essentially, if it is bleeding). This is the care I suggest you follow: http://www.safepiercing.org/piercing/body-aftercare/ You should do so until it settles down and seems as healed as it was. That could take several weeks, depending on the extent of trauma from your little accident.
Here's a section from my book, The Piercing Bible--The Definitive Guide to Safe Body Piercing, about trauma:
Rubbing you the Wrong Way: Friction and Trauma
Physical trauma is one of the biggest dangers to your new piercing, whether it is caused by mechanical stress from the movement of your body, accidental bumps, or pressure and friction from clothing. Repeated trauma leads to inflammation and edema (excess fluid in the tissues that causes swelling), which interferes with local oxygen supply. This reduces your ability to process the wound effectively. Over the long term, friction on your healing piercing will cause complications, including irritation, delayed healing, and ultimately scarring and migration or rejection. To minimize trauma to your healing piercing, follow these guidelines:
• The temptation to play with your new jewelry can be almost overwhelming, but you must resist in order to both avoid trauma and maintain good hygiene.
• Wear jewelry of the proper size and style to minimize friction.
• If your jewelry fits properly and is of high quality, leave it in during the entire healing time. Changing it unnecessarily can damage the fragile tissue.
• Do not handle your piercing roughly during cleaning.
• Avoid cloth towels, terry washcloths, and loofah sponges. The little loops on these materials can catch jewelry and cause damage.
• You may have to modify the position you sleep in to reduce pressure against your piercing. If you are a stomach sleeper, you may have to temporarily sleep on your back or side to protect a navel or nipple piercing. You also may need to adjust the way you rest your head on the pillow if you have a healing ear or facial piercing.
• To avoid accidentally catching or pulling your jewelry, be aware of your actions and the presence of your piercing.
• Take care not to bump or catch your piercing when donning hats, eyeglasses, sunglasses, and so on.
• For below-the-neck piercings, try to wear clothing or underwear that minimizes friction.