Hi, Welcome to Health care magic forum. The cause could be any thing, may be alcohol, deficiency, tobacco , etc. The quantity is not a strict factor. If intolerance is not dependent upon the quantity. Once not suitable, means may be effective,with even little quantity. I advise you to consult a physician for diagnosis and treatment. Take more of green leafy vegetables, pulses, sprouts, and protein rich foods. wishing for a quick and complete recovery. Thank you.