Each symptom is it's own kind of Tree.
That is what "ague" or "nausea" can start to feel like, inside.
I guess what I mean is, what if you could find fever in the center of some landscape, taking a formal shape. This Fever Tree, lush and strong. This particular one is new. But the species itself, old, a part of history, dotting itself over the geography of other bodies.
But it's really too high right now for me to tell you about it. Maybe when it's gone I'll know it didn't make sense anyways.