There are a variety of treatment plans available, depending on the cause of your nail trouble. Nail fungus may be treated with an oral antifungal medication, but creams typically don't work against fungus. If you have a simple infection, it may go away on its own. You should talk with your doctor if you develop an abscess.
If an underlying medical problem is causing your nail disease, you may also need to see a specialist. For example, psoriatic arthritis – a nail disease linked to the skin condition psoriasis – is treated by a rheumatologist (a doctor who specializes in treating arthritis) as well as a dermatologist.