Girls, the child is exactly two years old and his nail condition is te…

Girls, the child is exactly two years old and his nail condition is terrible ? In November we vaccinated, after that in the same month he got gastroenteritis, I suppose that's when his immune system was very weak ? A month ago we did blood and urine tests, they said everything is ok, except for a little hemoglobin needs to be raised. To whom should I turn? Please tell me ??