Light, or clay-colored, stools are associated with a blockage of the biliary ducts. Normally, this is associated with gallbladder or liver disease.
To evaluate for this, you may want to consider an abdominal ultrasound and liver function tests. Normally, if there is an obstruction, the bilirubin level will be elevated.
If these tests are negative, you may want to consider an upper endoscopy to evaluate for various causes of dyspepsia (i.e. GERD, inflammation of the upper digestive tract, or ulcers).
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Thanks,
Kevin, M.D.