A week after swimming during a family vacation, 4-year-old Frankie Delgado died from a rare condition known as "dry drowning."

The Delgado family told CNN that Frankie had been playing in knee-deep water during a Memorial Day trip to Texas City Dike when a wave from a faraway ship knocked him over and went over his head.

At the time, a family friend had picked him up right away and he had said that he was okay.

"He had fun the rest of the day," his father, Francisco Delgado, told CNN. "I never thought nothing of it."

The next night, Frankie began to vomit and had diarrhea — but since his parents had taken him to the doctor for the same symptoms before, and had been told that he had a stomach bug, they decided to treat him at home.

Over the next week, his symptoms continued, and his parents called 911 when he complained of shoulder pains and tried to take a nap.

"Out of nowhere, he just woke up," his father told ABC affiliate KTRK. "He said ‘ahhh,’ he took his last breath — and I didn't know what to do no more."

"When [the doctor] came in, she told us it's what's called dry drowning," his mother, Tara, told KTRK. "His lungs were full of fluid. There was nothing else they could do for him."

Dry drowning, also known as secondary drowning, can happen when someone inhales water through the nose or mouth, according to the American Osteopathic Association. The water doesn't actually reach the lungs — instead, it causes a spasm in the airway, causing it to close up and make it more difficult to breathe. The condition is extremely rare — James Orlowski, MD, of Florida Hospital Tampa, told Web MD that it occurs in only 1-2% of all drowning cases.

Warning signs can include trouble breathing, coughing, chest pain, and in Delgado's case, vomiting. According to CNN, doctors believe that his vomiting and diarrhea were early signs of the condition.

Though Delgado's death is still pending an autopsy, his parents want to warn others to help prevent other families from going through what they did. And it looks like they may have already succeeded — on Friday, a man in Colorado says that the Delgados' story helped him save his son from the same thing.

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"I feel like I needed to reach out to the parents of little Frankie and tell them, I don't know how to word it, but their little boy saved our little boy's life," Garon Vega told ABC. "There was a purpose. It was an unfortunate thing that happened, but if I had not told my wife that he swallowed the water, and if she had not seen that article, I think we would've ended up dispelling it as a regular sickness."

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