The problem with going to a class to address your back issues is that the class is designed without knowledge to your specific issues. Restorative can cause further issues to your back. It promotes flexability and mobility rather than stability.
I really suggest you speak to a physio who can assess then give you over to a trainer/kin or someone to design you a program based on his diagnosis. Or have the physio design you one (I don't know if you ahve benefits or the cash to pay for a physio for multiple sessions)
Are you a doctor?