My fiance has a rash on her hands and under her fingernails steriod cream from the doctors did not help what do you thibk it is?

See dermatologist. If already seeing a dermatologist (skin doctor), a person with a hands rash that is not going away should be checked by the dermatologist again. It could be that stronger steroid creams are needed, or it could be that the rash is a bacterial or fungal infection. There are also more rare skin or nail conditions that need more testing, and the dermatologist is the specialist in that field.