muffen

I have been having trouble with one of my three banana plants. They are planted near each other so they should all be receiving the same conditions. However, the leaves one plant (and that plant's pups) keep falling and hanging straight down. Originally I had thought that I had slacked on watering to much but I have become more diligent and the problem is actually worsening. Most of the new leaves fall over before they even unroll. Today I went out and the center shoot/stalk/plant had fallen completely (about four inches below the oldest leaf had bent over). I am not sure if I have any stakes to support this plant because the bend is about 3 feet off of the ground. Would if strengthen back up if I was able to figure out how to hold it up? How can I prevent the leaves (or the plants pups) from falling? What I find most unusual is that the other plants aren’t having this problem (they are all the same species, but I don't know what species they are). Thanks for any help!