Hi. So I've had this plant for several months now. It always has bright light and I water it a tiny bit once every 2 months. I recently transferred it to a gritty mix and then I gave it a cup of water. Now part of it looks yellow. Not too sure what is going on. It doesn't seem to be rotting but I fear if I water it again it will actually rot. Please tell me what you think. The yellow is in the middle of the crest near the bottom.