There is no need to worry, insha-Allah through this sickness, you will be cleansed and purified. (i.e. There is absolutely no need for you to worry or fear. You are merely undergoing a cleansing process. Spiritually, you are being cleansed from your sins, and physically, your body is being cleansed from toxins. Hence, when this sickness has come to you as a mercy in disguise from the side of Allah Ta‘ala, there is no need for you to worry and grieve).