This might sound heartless, but your DS will be well in time for your cruise. Your grandparents are our PARENTS age and if every time we have had a health scare with them and cancelled a vacation we would not have left in the past 15 years. If I were you I keep my original plans. None of your ailing loved ones would want to to cancel your trip because of them. Believe me - been there done that. Just my two cents worth.