Get your conditions right. Only water when the top 1" is dry. I think the biggest mistake I made when beginning was overwatering.
That plant is stressed from something... looks like overwatering... but could be multiple things.
Put your hand, palm down, at the height of the plant, under the cooltube. Does it feel uncomfortable? If so, it's too hot for your plant, move it up. Make sure you have drain holes in that pot. Add a fan to help dry the soil faster. Only use plain RO for a while...