You probably delinked to make an alt then tried to sign back into your main, email ata but they'll probably tell you to wait a year and then it'll go away :/
JT said what I was going to say. You cannot delink an account, create a new one then try to log back into the original one on the same device.
One account per device. If you have more than one account on a device you will be locked out or "expelled". Please remember this.