Question
I am a new phal orchid owner - 3 wks.  The plant is beautiful and still blooming, however, one of the bottom leaves fell off quickly after getting it home after turning yellow and wilting.  It was the 4th leaf on that side so I assumed it was natural.  However, now the 3rd leaf down is now 1/2 yellow and wilted.  (This same leaf had a black spot on it when I bought it.)  Both of the leaves in question are facing toward the window as opposed to the other leaves which havent shown any issues.  

It is sitting in my bathroom, in decently bright indirect light.  I am watering it every 1.5 - 2 weeks when it seems almost dry.  I havent fertilized it yet...  

What is this caused from?  Am I slowly killing it?  What should I do?
Also, what kind of fertilizer do you recommend I purchase?

Thanks  

Answer
Here are my recommendations:  First, let the plant finish blooming; second you should remove it from its pot and check the root system; remove any rotted roots which are probably the cause of your leaf problem: finally repot your plant in fresh orchid potting mix.   If all of the roots are firm and healthy, then we will need to look for another cause.  Chances are very high that you have a root problem that began before you got the plant. Once you can be assured that you have healthy roots and have repotted it you may resume watering and feeding.  Any kind of plant food is fine-- just use 1/4 of trhe recommended fertilizer concentration.