Many people mistakenly believe they have a 'healthy' diet, due to the misinformation abounding as to what that consists of, even from some professionals in the sector of diet and nutrition.
My bet is that you are deficient in certain nutrients, assuming there is not some other cause, such as high stress levels, trauma, etc.
Find a good nutritional advisor, or speak with Lambert's Healthcare whose informed experts maybe able to help and advise you for nothing!.
David