Dichaea sp. in trouble

[Bulbophile]

Ok so, I'm new to the forum and relatively new to keeping orchids. I just recently got into keeping miniatures, and got a couple on ebay. Out of the group, was a Dichaea sp. I asked the seller what species it was but he said the supplier he got it from was in mexico and they were unsure. So anyway, to get to the point it is yellowing at an extremely quick rate, it is only a cutting but it is well rooted and I was keeping it in a terrarium that I set-up to house a couple of my miniatures. (increased humidity) I've been using filtered water on it and i just recently changed it substrate because of a thrips outbreak. (just as a precaution, none of the miniatures seem to have been effected) So anyway, it got up to like 87 the other day, and I'm not sure if it was the heat or what. Even though it turned yellow, the leaves aren't wrinkled or anything. Any Help would be appreciated.

This is my first post, I've gotten alot of advice off this forum, because it often comes up in my searches on google. So thanks in advance.
~Kevin