Ditto you're likely overwatering, which is making nutrients less available. Have you repotted it since you got it? If so, what kind of soil did you use? It needs soil with some organic matter but more perlite than typical potting soil so it drains well.
I'd pull it out of its pot and look at the roots. They should be whitish and firm, if they're brown and slimy they're rotten, and those need to be removed. I'd also stop watering for a long time. If it starts to get droopy or shriveled leaves you know it's thirsty again