Check your fingernails.
Pale – anemia, congestive heart failure, liver disease, malnutrition.
White – Liver
Yellow – generally fungal – rarely thyroid, lungs, diabetes or psoriasis
Bluish – Lack of oxygen from lungs/heart
Rippled – psoriasis or inflammatory arthritis
Cracked or split – Thyroid
Cracked or split and yellowish – more likely fungal
Red and puffy nail fold – lupus or another connective tissue disorder
Dark lines beneath the nail tip to moon – most likely melanoma – see doctor ASAP
Bitten nails or picking – anxiety, compulsive/obsessive disorder – seek help