I'm not sure if your muscle numbness and tingling happens at the same time when your nails turn blue, but those feelings are always signs of Raynaud's if it's happening at the same time. My feet and ankles go complete numb and my arms tingle like they're asleep when my Raynaud's acts up.
Are you on any medicines like immunosuppressants? My liver became severely inflamed and they couldn't find the reason at first but it turned out since my immune system was suppressed I contracted an infection that went into my blood stream and infected my liver. Hopefully you'll get a diagnosis soon, I know how miserable the waiting can be
Also MCTD stands for Mixed Connective Tissue Disease which is an autoimmune disorder that mimics the signs and symptoms of three other autoimmune diseases - lupus, scleroderma, and polymyositis.
Hope this helps