Getting a cold is not normally a life-threatening emergency, but a South Bay couple says that could be the reason for his son's death.
Mark and Belle Ang have been in shock for two weeks Her healthy, lively and athletic 9-year-old son Tristan died suddenly.
Doctors believe Tristan's death may be due to a rare complication of the common cold or adenovirus.
"That's what they said Unfortunately, one of the complications is that it can go to the brain," said Mark Ang.
"Waking up every morning is a struggle for us," Belle Ang added. "At night you can not sleep."
The Angs said it started a week before one of Tristan's Taekwondo contests. The third grader, who attended the Marshall Pomeroy elementary school in Milpitas, was a big fan of the sport and also a black belt. Mark said that Tristan had become a bit weak, a bit tired, with a headache, fever, nausea and vomiting.
Doctors sent her home from the hospital and said he was just dehydrated. But a few days later, he looked dizzy, trying to pronounce his own name.
"I was so worried, worried that I told my dad you can keep track of the other two, we'll go back to the ER," said Mark Ang.
When he was in intensive care, swelled Tristan's brain and soon his heart stopped. Four times.
"After the fourth try, the doctor told Belle and me that he was dying," Mark said. "As a nurse, I know, but as a father, I do not want to believe it."
Tristan had disappeared within three hours.
Neither Mark nor Belle, both nurses, could believe it.  "We blame ourselves, what did we miss?" Belle said:
The Angs have two other small children, but Tristan was their first child and they had been trying to have him for 14 years.
The family wanted to donate Tristan's organs to another patient, but said he was not eligible because he had the adenovirus.
A GoFundMe site launched on July 1, commissioned by the Ang family, had raised nearly $ 8,000 on Thursday night for a $ 10,000 goal.