House plant seems sick

Question

I haven't been able to identify this house plant. Its leaves have a really beautiful pattern, as such:

It has been watered regularly, is in the sunlight every day, but the leaves are furling and yellowing inexplicably, and the stems are falling limply:

Inside the pot cover, the plant is inside a black plastic pot, sat atop an upside down pot that was trimmed, so the pot doesn't soak in water at the moment.

I thought that maybe it needed to be placed in a larger pot, so I took it out of the black plastic pot, and noticed the roots were very dense. At the bottom of some of the roots, there seemed to be bulbs. I wasn't able to find a larger pot at the time, three days ago.

I recently gave the pot new soil and plant food and yet it is still looking sad.

What does this plant need?

Answer 1

This plant looks like a Ctenanthe (https://whatflower.net/houseplant/ctenanthe/). Or one of its realitves of the Marantaceae family (https://www.google.com/search?q=marantaceae+varieties&newwindow=1&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjp-vmUwrDhAhWTF3IKHc1oD04Q_AUIDigB)

It looks very much like overwatering, but you already checked it. So if the roots are white and not rotten (which means it was not overwatered), you can check these factors:

1. Air humidity (did it became very dry or hot recently)
2. Temprerature (was the plant exposed to cold)