Please don't do deadlifts and only deadlifts, it'll end up as yet another repetitive movement in the inventory of things executed with shoddy biomechanics. It may work for now but some years down the line those bad habits that caused the issue in the first place will catch up again, probably in another place, rinse and repeat, unless you re-build all your movement patterns to not include those bad habits.

Baseline should be something like Physical Therapyish mobility and/or Callisthenics core strength, note in just how many different ways the callisthenics stuff works on the same thing while including the opposite for balance, while the PT stuff goes through basically everything that can possibly be tight. Both will make lots of muscles that you didn't even know you had complain very loudly and learning about "new" muscles, how to activate them and what to do with them is how you fix your shit from the ground up.