Yes, it is possible for milium to disappear and then reappear. If the bumps persist for more than 3 months, it would be best to consult a doctor. The causes of milium are not fully understood, but hormones may play a role in some cases. It is important not to apply oily or moisturizing creams on milium, but instead wash the affected areas with warm water a few times a day and gently pat dry with a soft towel. Avoid using cleansers, picking or scratching the bumps. If you have any further questions or concerns, feel free to reach out for more information.