Could you post a picture? It will help determine problem with your root rot.
What is your watering regime? What its potted in (what kind of pot, medium)?
Usually root rot is outcome of over watering.
By stems do you mean spikes with flowers?
If i would you and have phal with little roots and spike i would cut off the spike to let energy go to root growing instead of keeping flowers
You might need to repot your phal.