What is wrong with my dendrobium?

[jaxorchidman]

Definitely spray with fungicide. I would also put it in a more coarse media mix. If it was growing in rocks before you got it, the roots were acclimated to a free draining media and something that fine might start to rot the roots. Just my opinion. Someone else will tell you theirs also. Good luck. It should be a nice antelope hybrid. Den. helix is very hard to find. I haven't been able to locate one yet.