Thanks for writing to us.
Lower back, hip and pelvic pain
is common after childbirth. In most cases it's occurs due to deficiency of vit D3 known as osteomalacia
You need xray of lower spine and pelvis to diagnose your condition.
You need proper vit D3 supplements. You can take this after prescription of your doctor.
Avoid forward bending and heavy weight lifting.
Hope this will helps you
Wishing you good health...
Dr Saurabh Gupta.