BlindPigeon76
First off you need to speak with your brother to find out if he accessed your account and how? or whether it was hacked?
As EA_Aljo Mentioned other than advice we (The Forum) cannot help with account actions, please use the link provided.
If you gave your brother access to your account and they did bad stuff on it and got it banned that is not good and even though it is not purely your fault it is still your fault. EA does not allow the sharing of accounts, it is against the ToS.
Do not let others use your game account (Friends and family alike) because if they do something wrong on your account it is still your fault, nobody wants to have a sanction on their account because somebody else did or said something wrong.