The other possibility is iron and Vit
B deficiency. Along with multivitamin
B (not a multivitamin which also has other
vitamins) take an iron preparation and see.
They can also be caused by allergies and infections. You could either be suffering from contact dermatitis or from allergy to some food. You should get an allergy test done, either a skin test or RAST, to know what you are allergic to.