Hello Dear and thanks for questioning.
Your problem is more likely to be related with spine and you should consult your nearest orthopedics. The other cause might be lower S. Calcium Level but it was not occur at the age of 20. The pain and morning stiffness
are the symptoms related to RA. For this I needs your some history like
Have you undergone fever
for a long time more likely at the age of 13-15? Is your pain continuous?Have history of any trauma?Family History?
Please reply me or get your nearby ortho consultation.