I think that was debunked. Syphilis is actually present in all regions, and previously spread throughout eurasia.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3956094/#:~:text=Throughout%20the%20centuries%2C%20syphilis%20has,prevention%20programs%20control%20the%20disease.

I learned a bit reading here. It was more mild according to that write-up, but evolved to become more brutal. Interesting point, it mentions that in Europe it was mistaken for leprosy, so she may have decided to be sealed in due to the similarities in her condition. Hard to say.

Probably contracted it before, or was abused by someone with it before she became a nun. Lots of women that were victims of abuse were shuttered away in convents to hide what was done, or were sent there for their own protection. Not a good time to be a woman

Don't worry a volcano will erupt and the end will be nigh! Those mega volcanoes always know when to dump a load to end some crazy streak

Its kind of ironic that something similar happened around the time of Constantinople's fall. Environmental conditions have a huge impact