Please help

You,have not really given us much info about your culture to go on, but that photo says a bunch.

Start by getting it out of that glass vase! Orchids do most of their respiratory gas exchange processes through their roots, rather than through their leaves, as is the case for terrestrial plants. A very poem airy potting medium in a more standard pot will permit you to water more thoroughly, more frequently, providing more water (the driving force behind growth), flushing residues and plant wastes, while allowing more air to the roots.

 

I think we need to get square on some terminology, while we're at it:

The plants you have are both sympodial, meaning that they produce new growths from a rhizome. Each growth is actually an individual plant, but several of them will be hardier if left together as a colony.

A keiki, on the other hand, is typically the emergence of a new plant from the inflorescence, and as Marni so clearly stated, is often a reaction to distress.

Just a guess on my part, but I suspect that, when you repotted that plant, the nases of the new growths were somewhat higher than that of the existing growth, so you potted it up deeper to compensate. That led to the death and decomposition of the roots and rhizomes that were too deep.