Bifoliate loosing leaves and turning black

[luvmyorchid]

Hello Cattleya gurus! So I have this bifoliate in the last two weeks abort it's new roots and looks like the newest growth is turning black. Also is loosing leaves but seems to be on oldest growths. I'm feeding msu weakly weekly and flushing and also do kelpmax once a month. It lives under Jeff Young's grow lights in 60 to 75 percent humidity. I'm so scared for my other plants this is the only one doing this? I haven't repotted due to the fact it aborted the new roots. Almost like rootburn? I am at a loss.....please guide me fellow orchiholics!