Judging by your age you may have just passed through menopause. When I did I gained 20 pounds. Eventually I lost 15 of them without even trying. It might just be that kind of hormonal screwup. However I did not have any pain, although carrying the extra weight in clothes too tight for me was uncomfortable.
any new meds.and or steriods dibeana
What type tests have the doctors run? Ultra sound? MRI? The fact that you are experiencing pain is far different from my weight gain or that of others I have read. If they haven't run the entire gambit of tests...I would push it. So many of us women have sudden weight gain ( I am 5'3 and gained 30 lbs in 4 months and no one knows why...but I have no pain). Good luck.