I'd like to add that what you think is your hip bone is really the upper arch of your pelvis; the hip joint is located in the crease where you leg meets your body - your groin. If the pain is in your groin, it's the hip joint. If it's anywhere else, it's the pelvis. :)
I know this may sound strange, and may not be the cause, but check to see where you lean at the sink or vanity in your house, or maybe your desk at work. If the height of the vanity, etc, lines up with the indentation, it could be the problem. If you spend time every day leaning against your hip, it will eventually cause an indentation. And I guess it could cause pain too. I had one on my upper thighs (but no pain), particularly my left one where I leaned to get close to my mirror over the vanity. My massage therapist even noticed it and thought maybe I had some muscle atrophy, which it wasn't. I just stopped leaning so hard on it and it totally went away after a few weeks. This would be something easy to try. Hope it works for you too.