Can’t change EA ID back to old EA ID

I’ve been  using this account for a while linked to my Xbox, (the account was originally called meganinja9), I hadn’t been using it much but a few weeks ago it said that I had to reset the password to play online. After finding the information that I needed to do so, I reset the password, signed in, and restarted my console. When I got back into the game however, it said that I still had to reset the password, but not only that, the EA ID was changed from meganinja9 to jumbled mess of letters and numbers. I can’t change it back because it says that the meganinja9 EA ID is already in use. I can’t unlink meganinja9 from my Xbox because I can’t login to it and I can’t link this account to my Xbox because there can only be one EA account linked to my Xbox.