Help with wilting yellowing leaves on young phal.

[Lizzles]

Hi there,

I purchased a new orchid recently and some of the leaves are wilting a turning yellow with some strange discolouration. It is a young phal, I first thought it could be a light issue so I moved it from the windowsill (which is north facing and doesn't get much light anyway), but I'm really worried it could be something more serious! The top two leaves are ok, but I'm worried the problem could move to them too. Any ideas what this could be? The roots and blooms are both very healthy. Could it even be shock and moving environment? Any help/advice would be greatly appreciated!

Thanks!