Little leaf on Phal has started to turn black

[Orchid grower]

Hello everyone!

I have an orchid that has grown two new leaves since this past summer. The newest of the leaves never grew very much but I thought that might have been due to the colder weather. Recently the leaf started to turn black and is spreading. I've attached a picture. Does anyone know what might be going on?

I previously thought this Orchid may have a fungus issue because when I purchased it summer 2017 some of the flowers would start to get these see through dark areas, almost like someone was wiping the colour off the flowers. I've attached a picture of that as well.

I really don't want to throw this plant away. It showed very healthy root growth and has the most beautiful orange flowers.