Talk to Orthopedic on Lower Back Pain

i have a bad posture, lower back Stiff muscles and our office chairs are also not comfortable but the ceo have purchased the Molti brand expensive chairs so is not willing to approve any change. even for my 5.2' height type person is not able to have flat fret on ground as chair lower limit is not that much low. also i have too much deficiency of Vit D and cant use regularly as it increased the Kidney oxalate calcium stone so i am kind of stuck and having sever pain in lower back. plz guide