Suggest Treatment For Right Lower Back Pain

I have been experiencing pain in my right lower back for several months now that is much worse at night when I am lying down to sleep. There is no comfortable position that provides relief. It is still there during the day, but is reduced to a mild aching feeling unless I turn side to side at the waist. I don t have a family doctor because I am typically healthy and just go to see my OBGYN annually. I am not sure where to start or what type of physician I should see and of course my biggest fear is cancer. ANy thoughts? Thank you! Candace