Hi,Welcome to HCM.I studied your query.I understood Your concerns.Dear you seem to have a painless movable lump on hip bone.By its big size,In My opinion,it could be Lipoma/Sebaceous Cyst/ Fibroma/ or could be from a un-noticed hit-which seems to be less possible-as you don t have any history of it. Your query being with scanty information about the tumor,I would suggest USG and Second opinion and physical check from Surgeon.This would resolve the ambiguity in its diagnosis. Your various other problems of sacro-iliac pain/ pelvic flattening,osteomalacia,need to be worked out for any relation with this lump by X-ray/CT scan and Blood Vit D studies. Hope this reply would satisfy and would help you to plan treatment with the right consultant doctor. Contact with a Followup Premium question to ME.Will appreciate your Hitting thanks and writing excellent review comments to help needy patients like you. Good Day!!Dr.Savaskar.Senior Surgical Specialist M.S.Genl-CVTS