Neck pain in an young adult like you is usually due to muscular weakness/posture related.. Since x rays are normal nothing to worry.. Exercise and strengthen the muscles around your neck as advised by ur doctor..
Vitamin D deficiency rarely causes isolated neck pain..
Regards,
Dr NATARAJ H M
MBBS, MS ortho
MCH ortho(USAIM)
Fellow Advanced surgeries of shoulder and knee(Italy)
Fellow Arthroscopy and sports med(International society of AKOS)
Fellow Joint replacement(ISHKS)
ORTHOPAEDIC SURGEON AND SPORTS MEDICINE SPECIALIST