Respected members of the clergy, I am sorry for intruding, but I have an idea, although it may not be conventional, at the very least it does not involve using any dark arts.
I come from a far away kingdom, in that land my father is the king, which makes me a princess of royal blood, it is said that a princess' kiss has magical powers of a good nature, if it can turn a cursed frog prince back into his former self, perhaps it can bring back health to St Vitus since it is rumored he was cursed by Eudoxie. A chaste kiss of course, considering the vows taken by his eminence.
I can offer no guarantee that it would work, but since convenional healing magic has not worked thus far, I do not think we have anything to lose by giving this a chance. I am humbly at your service, should you deem the idea worthy to try. If successful, I ask for nothing in return, it would be rewarding enough if St. Vitus' health came back.