Take it to the Apple store, tell them, and ask for a replacement. They need to make sure your computer is fine, but they should replace the charger. If you have a flash drive, back up everything you can on it. Just in case they need to fix anything. Edited to add: If you don’t live somewhere with an Apple store, you may need to call them and it might involve lots of mailing and that would totally suck. I hope you live near an Apple store.