Yellowing spikes during bloom - phalaenopsis

[LilliePad]

Hello! I'm an obsessive indoor gardener and tried my hand at caring for orchids last year. I bought this phalaenopsis on sale at a grocery store last year at the end of its blooming period, and if memory serves, this will be its third set with me. (And it's been blooming since late march)

The tips of the spikes have turned yellow and is slowly progressing down the spike. I know it's normal for this to happen at the end of the spike's blooming cycle, but since none of the flowers are showing any sign of dropping, I wanted to make sure this wasn't something I could prevent.

Some information: I haven't re-potted it since I bought it, nor given it any kind of orchid food/fertilizer. It's been in the same spot since it started blooming, and I haven't changed its watering schedule (about once a week, or a little bit if the roots start to shrivel). Now it is receiving more sunlight due to the change in season (south-west second-story window), but I usually close the shades when the sun is directly shining through to protect the rest of the plants on my table. I've attached some pictures to help with the diagnosis.

Any help or advice anyone can give will be very appreciated. This is my first post here so it's nice to meet you all!