This section of the stem has looked constricted/oddly shaped since I purchased it a few months ago. It was otherwise heathy until yesterday. It looks like it is draining and becoming squishy. It turns yellow then brown. It's happening rather quickly and I'm concerned that it may spread to the healthy section if I don't intervene.
I've watered and fed it every 3-4 weeks with no problem. I keep it indoors at a fairly sunny window. It's been growing like crazy until now. It is still a small plant, about a foot tall.
Any ideas what this is? Disease/malnourishment?
Should I remove this section?
How (and where at) would I do so?