What is death and why does it happen ?

Hello, i am Emily from Finland. Last year i lost 8 months baby boy who died a few hours after we checked in emergency ward of the university hospital of Turku. The cause of the death was not known till now...I got pregnant again and i got a baby boy 5 months and he died 3 weeks ago with the same symptoms like my first baby and upto now we are waiting for any answer from the same hospital. The symptoms were a week before fever about 39 degrees centigrade and vomited twice...i took him to the hospital, they took all the necessary blood tests and urine tests and the results were OK...the baby was eating normal and playing normal in short healthy. A week later it was vaccination time the baby got 5 months normal vaccination and i explain to the nurse what had happened a week ago and she said it is normal with babies to get fever. The next after vaccination the baby had slight fever i gave panadol suppository and fever went down but he started breathing with difficulties...mostly using muscles for breathing. I took him to emergency ward and the doctor just told after examing the baby with stethoscope all is ok but i asked why is the baby using muscles for breathing which is not a good sign...The doctor asked me if it is because of fever or vaccination...I just looked at the doctor with no answer! hours later my baby died the same like the other and now we buried Sami on 4.8.2012 and still waiting for any answer why he died...PLEASE would you after reading the symptoms have an idea what could it be? I will appreciate and be at peace when i know. Thank you. Emily

my father died of a cardiac arrest. However, he had an abdominal aortic dissection that was detected on the last day. his intestines, gall bladder and part of the liver were removed. BP and pulse were high during the operation. later stabilised. then at 1.20 am, he had a cardiac arrest and passed away. He had no history of blood pressure, or heart disease.He first reported stomach, back n chest pain on 7th december, 2010. Also fainted and vomitted. However, doctors suspected food poisoning, colitus and later gall bladder inflammation. the actual problem was discover on 23rd Decemeber, he died later the same night.(24th december) I need to know how and why this happened