Hello there folks!

Very recently my bamboo has been yellowing from one leaf to the tip of its stalk, and it's spreading down quickly (comparison of two diff pics of its stalk are a day difference). I have been neglecting it and I think there's a specific issue I can't pinpoint. I've been taking proper care of it since this notice the past few days. Before changing my ways it was:

• in a dim corner in my room
• lacking a water change in over a week

There was more leaves besides the one yellow leaf that were completely yellow and dry. I peeled them off and noticed there's weird red lines around the yellowed leaf stem, and the node by it is white/gray compared to the rest below. Could this be a disease that caused it to die at the top?

Solutions I'm thinking of doing to help my plant boy:

• use distilled water instead of filtered tap water
• buy soil for the roots, and use a non-clear jar/pot
• possibly cut off the upper dead stalk and propagate the healthy leaf stem

I see multiple causes to the yellowing but I'm hoping someone might see something I can't. Thank you!