What are the symptoms of low vitamin d dose it cause aching legs and sore knees when bending or climbing stairs ?

Possibly: Vitamin D deficiency could cause aching legs and sore knees. A more common cause of knee pain in a young healthy woman is when the kneecap doesn't track straight in the groove. Pain worse with stairs is classic. Usually pain in the front of the knee. "patello-femoral pain syndrome". PT will help. Exercise to strengthen the medial quadriceps. good luck! :-)