It could be from eczema, nerves, jaundice, leukemia.......or just a simple allergy to chemicals.
You can have yourself checked for jaundice by a simple blood test. Benedryl isn't going to help you in this instance.
It is important to go to a doctor (probably a dermatologist) to be diagnosed if you do not have some sort of toxic problems with your blood, which is more serious and you should have checked first. A dermatologist will be able to give you an effective treatment if it is only a topical problem.