The first step would be to get a referral to a Rheumatologist. Rheumatologists specialize in disorders of the muskoskeletal system and disorders of the immune system. The rheumatologist will do blood work, imaging tests, press on different areas, and manipulate your joints into different positions. You likely wont get a diagnosis in the first couple of visits as these tests can take a while to get the results back. Fibromyalgia is a diagnosis that's made based on ruling other disorders out such as Lupus, Inflammatory Arthritis, EDS.
Being diagnosed with Fibro can be tricky. It is usually a diagnoses of elimination. This is often a long and stressful trip. Sometimes this can take years and several doctors. Be patient and learn to be your own best advocate.
In Canada. My personal experience.... My Doctor has ruled out All the others then he called it Fibro the changes it to chonic pain. They are reluctant to the me to a Rhematologist, because the say there is not much the can do and don't want to waste there time. .Lucky me. I don't get it, but it is about to Escalate soon.