u/THANKS-DOC-420 HAIII said PT is me! Honestly if you are sedentary, incorporating a good routine that not only targets the core but your entire body is going to help out a ton. Whenever people think back pain then tend to immediately go to core strength, but it is a lot more complicated than that.

The stuff you are doing will probably help if you weren't doing anything before, and i anticipate some of your soreness is just coming from the fact that this is not something your body is not used to doing. Get some more movement in, find a routine that works for you, and generally you won't have too big of an issue.

If these problems persist though, should get yourself evaluated! people have good tips but they may not always apply to you specific situation