@amykcpa
Hi, I hear your concerns. I had a lot of fear before my fibromyalgia diagnosis, and think learning what caused the pain and fatigue helped reduce my pain and fear (unfortunately, not the fatigue). Years later when I started having systemic joint pain, I wasn't all that concerned, but my rheumatologist was. After blood tests, x-rays, and ultrasounds, I was diagnosed with mixed connective tissue disease.
Like you, I searched for answers and found limited, not-very-helpful information. I teach exercise science, health, and wellness and am thinking of changing my research focus to MCTD so I and others with the disease can get some of the answers we're looking for.
If you want to talk or meet online, let me know. Sometimes talking is easier than writing. 😉