My Little Pony Friendship is Magic S02E06 720p

Summary:
Despite more advice in patience, Apple Bloom takes a shortcut to get a cutie mark thanks to one of Zecora's concoctions, not only granting her a cutie mark, but the unconscious ability to perform the talent it represents. However, this becomes a problem when more cutie marks appear on her body along with their talents. What is thought to be a mysterious phenomenon turns out to be a long-forgotten illness, and only Zecora knows how to cure it before Apple Bloom runs herself ragged.

Thanks to Ponyarchive.