The use of the category mental disorder is dated; disorders often have mental components but since the body has no clear separation of the brain and body, it's falling out of use. Also, it wouldn't be the first time a mental disorder turned into a 'regular' disorder, or that is was more of a stigma than an actual diagnosis. Which is why I think find it an interesting option.

As I said, the type of symptoms is broad, so it's unlikely to be one thing. But, I do believe medicine is slowly getting more serious about analyzing also the not clearly apparent symptoms.