Avoid gym . Posture correction must . PHYSIO treatment

https://www.youtube.com/watch?v=HxvRQ9ZJ8vQ Chiropractic Mobilization will help. Avoid bending in front. Postural Correction- Sit Tall, Walk Tall. Extension Exercises x 15 times x twice daily. Apply Hot Fomentation twice daily

everything while at gym goes fine untill you get stress and a simple jerk then it will give you pains. do regular gym, it is good but within your limitations depending upon you stamina. Dont get excited to build muscles, do.slowly and as guided by the coach. Better to hire a coach personally to train you as this will avoid any painfull activity that makes you feel comfortable.

Exercises will definitely help.with kyphosis. As suggested earlier muscle mass need not be the goal. As it does not have any particular advantage with preventing injury. But any movement based exercise with core stability exercises will help.