I believe this おめっち is singular "you" because this person is speaking to one person in front of him. おめ corresponds to お前. っち does not mean much, but it's probably a suffix explained here (oh, it's your question).
And this からかわれている is not "から + 変われている" but the passive form of からかう. から meaning "because of" or "out of" follows a noun that represents an emotion (e.g., 怒りから, 焦りから), but it does not follow a personal noun.
おめっちからかわれているんだぜ青山によ
You're being teased by Aoyama!