But i am fixing it. Starting the gym routine again and will resume some sports too. I re-started the session and not weights; more of core-strengthening and stretches.

You should storm the gym bro, Get back into proper shape. Aging while still young is not a good thing and it is caused by so many things including fatigue stress, one should try to rest no matter what, We are not robots nor bots and we can't always expect to over use our body and don't expect something in return. The body is fragile and it will definitely give up to fatigue and stress.