My bamboo plant is dying-please help!!?

I have a lucky bamboo plant that I bought earlier in the summer, and it was fine. However, the past few weeks, its stalks are turning yellow, and its just the two biggest ones, not any of the smaller ones. The leaves are perfectly green and thriving. The stalk is yellow, squishy and recently is shriveling. Please help me, i don't want to lose my plant!