Welcome to HCM,
As yoy have spondilitis of lumbo sacral region, it is possible that you might be having Sciatica
giving rise to pain in lower limbs
Due to stretching of nerve passing through vertebrae give rise to pain.
Rule out diabetes
Go for back extension exercise and other physiotherapy
Do not lift heavy weight and avoid bend at back.
Take B.complex supplements and calcium.
Ok and bye.