What is this on my leaves?

[Paul Mc]

Background: I bought this about a month ago and noticed some discoloration on the leaves but assumed it was from shipping or mishandling. I got it home and examined the roots and a lot of them were dead, so I repotted and cleaned the plant immediately. It's an Epidendrum "Fantasy Valley". Over the course of the next few weeks, many leaves shriveled and died which was not that surprising. However, now many leaves are exhibiting various stages of this zig zag black line, yellowing and wilting. Now, I'm thinking something else is going on. What could it be?!!!