Phalaenopsis leaves turning yellow

[OrchidsAreAwesome]

So I'm new to this site and orchids and I joined because my phal has a problem and I don't know what to do.

I received this phal as a gift about a year ago. It was doing great and even shot up another spike. About a month ago, the leaf on the opposite side of the spike turned yellow and fell out. Now the leaf above the spike is turning yellow and falling out. Yesterday I checked the roots and most of them are healthy and there was no root rot. I put my phal on a south facing window and I water it about every week or when it is dry.

I don't know what the problem is and I really like this phal and I don't want to lose it.

Btw, there is this little thingy growing out from the bottom of my phal and it doesn't look like a root of a spike. What is it?