So it's not welders flu.
According to my welding instructor with the materials we were using yesterday it's almost unimaginable that inhaling fumes caused my dis-ease.
We were using 7024 sticks on standard carbon steel. Nothing in that combination should cause Wlu.
Guess I caught that thing that's going around after all. On the plus side, I'm starting to feel better, so powering through was the right call today.