Hey Yan! I too am ahving the same problem. I know you posted in order to recieve some helpful suggestions, but i thought it would make you feel better to know that youre not alone right now! I just repotted my moth phal, which is also white. And I repotted twice too. And now i am contemplating whether or not to cut the spike. My flowers are falling off and my leaves aren't looking to great.
I repotted my phal because I noticed that there were a couple of dark brown and soggy roots (possibly due to watering too much especially with sphagnum moss -- but i learnt my lesson). So, after a lot of reading, I came to the conclusion that repotting my phal would probably be best for it even if it was while it was still in bloom. I read that phals are very forgiving and tend to thrive on new media..nso i repotted! I tryed a bark and charcole mix and after a few days, it always felt and looked dry, so I repotted a second time and placed it in fresh moss beacuse i can judge when to water them better in that.
Well, so much for helping my phal out! Now, my once beautiful white flowers are drying up and falling off! I have posted threads on whether or no i should cut the spike and a number of members told me to leave it be, however, if your phal is in such bad condition that it really starting to look like its 'going to go', than your best bet might just be to cut it and wait for it to bloom beautiful next year.
Goodluck! everything is going to be ok. Im in the same boat as you.
