A followup on the health issue I mentioned here. Short version: I'm probably fine and have been feeling better, and will be making some changes to ensure I remain healthy.
I had my followup appointment and can confirm now that I have an Issue which I will need to be cautious of but is not likely to be a significant health risk. Basically, I'm okay, I just need to stay on top of things to be sure I remain okay, and I feel confident that I can do that. I'm extremely relieved to finally have an answer.