I bought a plant a few weeks back and unfortunately it's not doing too well and it needs some help. I can't figure out what kind it is though. It is very similar to a calathea or a zebra plant, but it doesn't have the purple underside. It is simply light and dark green striped and it's going fast. The leaves continue to yellow and die. Any ideas what kind of plant this is and why it's dying? help! Thanks!!