lets start down the list: look for trigger, was there a tramatic event that triggered it (relation, marrital,death,over worked, not enough pleasure time) some thing you ate, not eating enough. How are your sleeping patterns?
possible
1. stress will shut down your digestive tract - reduce stress cut back on traning, mental, emotioinal, phyiscal
2. hormonal imbalance - too much or not enough cortisol - are you craving salt
3. hidden food allergies - diary, eggs, gluten
4. bacteria or yeast over gowth - excessive carbs fermentating
5. excessive caffine use - too much coffee over time
6. excessive sugar
7. dehydration - not drinking enough water
8. magnesium could be low
Re examine your lifestyle and eating patterns, sleeping patterns and make changes if neccessary.
is there any white coating on tongue?
are you a female and monthy time?
solution :
try to identify the cause
reduce stress through mediation, epson baths, reading a book, get to bed earlier, stay off computer after 8 pm if possible, getting not enough sunlight vitamin D can trigger stress
One can not just pin point one cause but has to look at the entire picture from mental, physical, spiritual aspects.
Fiber can make things worse..
everything in moderation do not shutgun