My albumin level is 3.8 and has decreased in the last year. my sister has non-alcoholic fatty liver disease. what should i do next? anything?

Nothing.: Albumin levels are useful only when monitoring known liver disease. Albumin levels fluctuate dependent upon many variables so I think you are probably NOT "decreasing." It would be distinctly unusual to find liver disease with an abnormality of albumin alone. Sister with NAFLD does not mean much for your health. See the doc who drew your blood.