It sounds like something impaired your digestive system and/or eliminated your intestinal flora to allow some imbalance to occur or parasitic infestation to begin.
Try to look back and think really hard about any life changes or events that may have caused this. Did you walk around in a lake barefoot? Swallow mud? Change living locations? Got sick and took a course of Antibiotics ? Get silver fillings in?
Work with any hazardous chemicals? Begun a different dietary routine?
Start with a thorough colon cleanse, then do liver flushes, parasite cleanse, supplement Iodine, then look into specific protocols like heavy metal chelation, candidiasis, etc.