BLOUNT COUNTY, Tenn. (WVLT) -- An autopsy is being conducted to determine exactly what killed an 8 year old Maryville boy who was diagnosed with an E. Coli infection.

Joseph and Jesse Coning were twin brothers who spent every waking moment together.

"Where Joseph was, Jesse was,” said Sandi Koeshall, the twins’ grandmother. “Where Jesse was, Joseph was."

That changed the first week of June when Joseph became sick while his family was vacationing on the Outer Banks of North Carolina. The sickness started as diarrhea, and then turned in horrible stomach cramps which promoted family members to rush Joseph to The Outer Banks Hospital in Nags Head.

“We were just wondering, ‘what is it,” Koeshall said. “They were just not giving us any diagnosis. We just know he's very sick."

He was next taken to a children’s hospital in Virginia, then flown to East Tennessee Children's Hospital where his health became progressively worse. He died early Monday morning, less than two weeks after first showing symptoms.

"He's not hurting anymore,” said Koeshall. “We're all hurting, we're hurting real bad."

Before his death, doctors diagnosed Joseph with E. coli, an infection caused by a bacterium known as Escherichia coli. E. coli bacteria is most commonly found in the lower intestine, and can cause sickness if you come in contact with fecal matter.

In the days since Joseph’s diagnosis, his family has wonder how he may have come in contact with the bacteria.

"The only thing we can come up with is they were taking swimming lessons in the pool in Maryville," Koeshall said.

Doctors at East Tennessee Children's Hospital say you can indeed get E. coli from a swimming pool. They remind parents to keep kids out of the water if they have diarrhea.

"If anybody has diarrhea they shouldn't be in the swimming pool,” said Dr. Jeffrey Abrams. “Make sure you wash your hands and don't let a diaper leak anywhere."

"I feel for all of us, but I feel for Jesse,” said Koeshall. “He's lost his buddy.”