I happen to have my daughter here, who is a professional body piercer, to answer your question. Her response:
It is most likely not a keloid, since a keloid is a rare genetic disposition. It is most likely hypotrophic scar tissue, which is very common with cartalige piercings on the ear as well as nostral piercings. That is often confused with keloids.
The hypotrophic scar tissue is scar tissue, and is most likely caused by a physical irritation. The most common mistake is from people twisting their piercing. Do not take out the piercing to clean it, or rotate the jewelry. This damages the fragile healing skin cells, and will create a build up of scar tissue. Thankfully, it’s not perminate.
You can get rid of it by figuring out what the irritation is (sleeping on it, twisting it, letting your dog lick you), and avoiding it. You can do sea-salt soaks, a quarter teaspoon of non-iodized sea salt and 8 ounces of bottled or distilled water. (the measurements are important. Too much sea salt will burn it) Soak piercing for 5 minutes twice a day. There can be other treatment options, but it is best to talk to your local friendly piercer, and there is great information on the association of professional piercers web site, SafePiercing.org