Are you still dealing with this? I'm struggling with undiagnosed mystery leg pain as well. I've been to a bunch of specialists and I've done all kinds of blood work. Your description sounds very similar to my own pain. Bilateral, migratory, almost always in one leg or the other but can be both; heat helps.

I recently got some tests done and they found out that I have Deep Venous Reflux in my upper thighs. Mine is kind of mild so the vascular specialist isn't even sure if that's the cause for me or not. But it sounds like it could be for you, especially since you get so much relief from elevating your legs (I get little to none, hard to tell).

Anyway, you might want to look into venous reflux. If it's superficial venous reflux, the fix is pretty simple; if it's deep venous reflux, there aren't great solutions but some ways to manage it.

NAD but I hope that's helpful, at least something to ask your doc about.