Turns out they didn't.
I have a deficiency of vitamin B12, with a recommended treatment of a vitamin supplement. That particular deficiency would explain not quite all my symptoms, but basically every single major one aside from the sore throats and cough. Including the fever, and including a symptom I forgot to mention when visiting the doctor (that I occasionally look pale, especially during tae kwon do, something which my instructor gets concerned about).
It'd also be, in one way, an answer for some of my cravings. For instance, B12 being necessary for absorbing iron, a deficiency of it would by proxy cause iron to not be where it needs to be, so I'd crave foods rich in it, something which has happened!
It may not be an answer for everything (for instance, nausea), but it seems like it's probably the main culprit, and things related to the B12 deficiency are probably secondary culprits, so treating it should treat most of my problems. Not all, but enough to get me on the road to recovery.
Blood protein levels were also elevated so I need another test to sort that out; my girlfriend suspects my diet which is incredibly protein-rich is to blame. (In my defense, I get an overabundance of carbs already, so I frequently feel like I NEED the protein-rich foods. I probably don't get enough fat in my diet tho.) And my girlfriend is probably right, so I'm not too concerned there.
I did have a small amount of red cells in the urine test I had, but no infection was present; I'll need a retest in a couple of weeks for that, but the doctor thinks this is unrelated to my current problems and that it probably won't be present again so is likely nothing at all.
Overall, this is pretty good news. With the treatments I am receiving, with luck, I'll start to improve soon.