I think my small avocado plant is dying.
I spent 15 days somewhere else for my holiday. Before I left my plant was perfectly healthy and lovely (photo below).
I told my roommate to water it on Dec. 28, at that time he took a photo and it also looked OK. By the way, I normally water it once per week with half a cup of water (the rice cooker cup, not a normal cup).
But now it looks like this (photos below, it's taken in my office, and it's not a heater near the wall), I am very worried.
I want to know what's causing that (disease, lack of water, too cold), and how to save my poor plant.
More details: I kept it near the kitchen window of my apartment ever since it was a seed. Because it can grow this tall, there shouldn't be anything hurting it, right? The only thing I can think of is that it's close to the window, so when it gets very cold outside (location: Cambridge, MA), it can feel the low temperature. Again, I am not sure.
Please help! Thanks.
update Jan. 29, 2020
I am happy to post a new photo of my plant. It has recovered and is now growing well. Actually--I could be wrong--the leaves are so large that I am a bit concerned it will quickly exceed the capacity of the jar. Anyway, so far so good.