I can only tell you what I would try to do in a similar situation First, if you can afford it, spend the money to have Sequencing.com or Dante or one of the other labs do a Full , Whole Genome Sequencing. It is a dirty shame that such a first step for your needs costs so darn much. But I like Sequencing.com because for a few hundred $ you can get several potential answers. Then run through at least some of the tests such as autoimmune or pathogenic or others to see what S.C has come up with. I suspect, just from the sound of things, some sort of Myeloma, especially Amyloidosis. Also look carefully at blood cancer, liver and/or kidney issues. And, talk to a genetic counselor and experienced diagnostician for added help. With this much I would bet you will have at least 20 solid clues. And don't rule anything out. I laughed when S.C suggested Sickle Cell, known as a Black person's disease. Then I remembered that 5 or six generations back, my ancestors thought they owned Black slaves, and did take into the family a few orphans left over from the Civil War struggles. And previously, we were world travelers, including economic jaunts into Japanese, Iceland, Vikings, Portugal, etc., picking up small lots of genetics from every continent.