The bone that you are referring to is called pubic bone and this should normally be flat and not prominent. The important causes of this bone coming forward are any swelling inside the bone, deformity of spine or deformity of hip joint. All these three things have to be checked by examination and if necessary by X-ray. The same deformity can also be present because of vitamin-D deficiency in childhood and evidence of this will also be seen on X-ray. I advise you to consult an orthopaedic surgeon for examination and proper diagnosis of your condition.