How do you get rid of bumps on the back of your ear cartilage piercing?

This is called hypertrophic scarring. It is caused by the jewellry putting pressure on the ear, and making scar tissue build up around the area of the piercing. You should soak it once or twice a day with salt water or tea tree oil in some warm water, and change the jewellry. If you have a hoop/curved jewellry you should chage to a straight, and if you have a straight chance to a curved, This changed the pressure on the piercing and allows it to go down. If you have an industrial piercing, you should put two separate pieces of jewellry in until the scarring has gone down. Try to avoid touching the piercing as much as possible.

Get some tea tree oil - you can get it in the natural section of beauty supplies or online. Rub some on the bump a few times a day. Massage it in well and make sure you rub the bump a lot to help break it up a bit. I'm not sure why it works, but my piercer gave me that advice and I've managed to avoid getting keloids so far. It works to get rid of them or to prevent them from forming in the first place.