Thanks for the query to H.C.M. Forum.
Post operative pain may be there , due to minor surgical trauma. ( id this pain occurs after surgery).
If pain was before surgery than you have to think,as may be due to,
Lumbo-sacral region straining or stretching ,Pelvic inflammatory disease
Poor bone density
Low calcium level,
Inflammation of bone ( back side).
Consult a physician / gynaecologist and get their opinion.
Physical examination will also play an important role in diagnosis.