Which Specialist To Consult For Internal Pain After Removing Indentation On Hip?

friend at work showe me an indentation on her right hip to buttocks area that is about half the size of your fist. she has had it biopsied, has had an mri done and lab work. nothing is showing up. she had these tests done through a good semarian clinic. now she has insurance and wants to know where to go as there is worsening pain with this extending internally. what specialist would she start with to pursue this? maryann