Hi Toni, if you have chronic widespread pain and no source for it has been found, you may indeed have FM.
When you mention your lower back, though, I am thinking you might want to have someone take a close look at that area. You might have degenerated discs or some other specific back issue that you should know about. this doesn't mean you do or don't have FM, of course. But I have degenerative disc disease in my lower back, and it's a good thing that I am aware of this because it means I have to be more careful how I move, how I bend, how I pick up everything even if it is lightweight, what kinds of exercise I can do and how, and other things. For me, it's not going to get better, but I can possibly slow down the degeneration. Not saying you have this, but I encourage you to look into it in case. The more information we have about what is for sure going on with our bodies, the better care we can take of ourselves.