That's right. Something about a Crystal, how it aged him, and would have eventually killed him outright.

[The details of all Regis told him get a little hazy beyond that, as he was trying to focus on actually cleansing the wound. Carlisle had a lot on his mind then; he still has a lot on his mind.]

Such artifacts can leave residual magic within the body when used, and much like a physical wound, it festers.