The "slime" is usually nothing more than bile and mucus from the intestines, excess can be a sign of Irritable bowel syndrome, food intolerance's, excess acid/reflux but most often it is caused by...
Mucus may lighten the color of stool, but it will never turn it white.
You very likely have a liver blockage. A substance called urobilinogen gives stool its dark color. Urobilinogen is a product of...