Why aren't doctors, especially researchers, more interested in defining the different muscle pain qualities in more detail? Does it give them no extra information? If so, why?
Pain is such a difficult topic! On the one hand, healthcare people take it quite seriously in that it is considered a vital sign, right up there with pulse, respiration, and blood pressure. On the other hand, it's much more difficult to assess and measure than other vital signs.
I put some of this down to the difference between objective and subjective clues. Subjective things are the ones that are entirely dependent on a person's individual situation: their life history, their personality, their unique physiologic make-up. They aren't accessible to observers except through telepathy, which people just haven't invented yet, and they may or may not be an accurate reflection of reality. If you have a mental illness like depression, anxiety or bipolar, I bet you can think of times when your impressions of a situation were really, really out of touch with reality and you needed a friend to get you back.
Objective things are the ones that everyone can see and experience without the need for telepathy. In a good way, objective is a way of saying "shared reality" rather than "personal reality". A philosopher might call objective stuff "the fact of the matter" or a religious person might call it God's omniscient perspective. This is where we start to get into trouble in healthcare. Healthcare people are encouraged to see the patient's perspective as subjective-personal, and may or may not be reality based. They are encouraged to see their perspective as objective- non-personal, unbiased fact. I bet you can see how that would be problematic. This is where we get doctors saying condescending things like "The symptoms or real but the disease isn't" or "I know you
feel that way, but...".
"All in your head" is the ultimate way of saying it's just a subjective issue, not a real (meaning objective) problem. It's why so many treatments for fibro are aimed at changing the perception of pain, not the cause of the pain.
So the problem of pain is really complicated. Even when I listen to my friends talk about it-people I believe and care about- it can still be hard to figure out exactly what they are feeling. If a healthcare person is listening with a bias that your pain is "just a perception" and not "real", meaning subjective and not objective, there's very little chance they will figure it out.