That is too much settling, in too little time!
I think the footing is inadequate.
You can only patch and hope it reaches some state of permanency.
In all probability I would get out and have a properly built home
constructed.
The Southern Standard Building Codes are minimal standards written in
cinjunction with the Banks to insure that the homes they were financing
would last the term of the loan 30 years.
It doesn't sound like yours meets that even.
Sorry. This is just my opinion.