First of all, relax. You aren't going to die, and you are not an alien. The reason that your doctor was surprised and called your parents is that blood type HH is a rare blood group also called Bombay Blood group - it is only present in about .0004% of the human population.
Blood type HH is different from the common blood types of A, B, AB, and O. Blood type HH does not contain the specific markers (or antigens) for the ABO blood group system. What this means is that you CAN donate blood to any other person, but you CANNOT receive blood from any member of the ABO blood group. If you are infused with the A, B, AB, or O blood , you will have an immune reaction, as your body will reject the blood of the wrong type.
You can receive blood, but only from other people who have Bombay phenotype, type HH. Given that this condition is very rare, if you need an urgent blood transfusion, you will probably be unable to get it, as no blood bank would have any in stock. Since those with type HH (Bombay group) can only be transfused with blood from others with type HH (Bombay group), you will need to take extra steps to ensure you have access to blood if needed. Those anticipating the need for blood transfusion (e.g. in scheduled surgery) may bank blood for their own use (i.e. an autologous blood donation), but this option is not available in cases of accidental injury.
It is very important to inform all healthcare personnel of your blood type immediately. The reason for this is that the usual tests for ABO blood group system would show your blood type as group O (since type HH is so rare, tests for it aren't automatic). Therefore, notify the hopsital to test for Bombay group. It would also be beneficial to wear a medical ID and carry a medical card indicating your blood type.
Best of luck.
RN, BSN, MS