My mom had it done and insurance paid for it plus they found her cortisone levels were very high so they were better able to help her.

There is a test it measures your cortisone levels to see if your body is expelling cortisone which means you are in chronic pain. So if you get the test and don't have an obvious ailment such as a broken leg , it's a good way to test for fibromyalgia

It exists... it's called the FM/a test.

I have read about it and am interested to see what my rheumatologist says about it.

It's usually something they mention if you are in extreme pain, my mom has fibro but also has degenerated disk disease so for her it was very necessary to test .