Go back to the place where it was pierced. They sell products there that you can use to put on your nose to help it heal properly. If you want to use a home remedy, put peroxide on your nose several times a day. This should help.
It's important to remember that you must have clean hands when touching your piercing. You should clean the piercing with antimicrobial soap and flushing it with warm water. After cleaning, the piercing should be soaked in a sea salt soak. Several daily sea soaks should help it heal it better.
get some rubbing alchohal or some other kind of disinfect an clean it. You may need to remove your nose piercing an get it redone in another spot. To avoid this from happening again make sure you clean your piercing twice a day.
The best thing to do would be to go back to the piercer and have them clean it out and remove the piercing right away. They should give you some medication for it.