After everything you've done to make the opener that just plain sucks and I'm sorry it's come down like this.
Where are they hypothesizing that the infection came from? Those internal infections are weird. Sounds like they are pretty concerned about it.... is it something you got from the ankle surgery that's been latent in your body? My SIL had that happen, in her elbow ironically, though it was contracted through surgery on that elbow. Almost lost the arm to some super-resistant bug born and bred right in the [bleep] hospital.
