Updated

What 13-year-old Marquel Brumley initially believed was a common cold turned into a deadly infection — and his family is sharing the boy's story to warn others just days after his death.

"Marquel was healthy; he had no health issues at all," Brumley's aunt, Nicole Alexander, told Fox News.

The eighth-grader went to an urgent care in Flint, Michigan when he started to notice cold symptoms. He was told it was a sinus infection caused by a virus and would likely get better on its own.

"A sinus infection does not typically need to be treated with antibiotics in order to get better," the Centers for Disease Control and Prevention (CDC) explains on its website. "If you or your child is diagnosed with a sinus infection, your healthcare professional can decide if antibiotics are needed."

Brumley continued to suffer from the cold symptoms for weeks and soon started to experience severe headaches.

He visited the emergency room several times. Each time, doctors diagnosed him with a migraine and he was eventually sent home.

Last week, Brumley's pain was so severe he returned to a local hospital for treatment. It was there that doctors discovered the sinus infection had spread to his brain, causing multiple blood clots.

He was transferred to C.S. Mott Children's Hospital in Ann Arbor, Michigan, where he was rushed into surgery. The teen suffered multiple strokes due to the infection and was left in a coma.

"The doctors [did] everything they [could] to reduce the pressure in his brain," Peggy Gilbert, another relative of the boy, explained in a post on a GoFundMe page, which is raising money to pay Brumley's medical bills and cover funeral expenses.

Brumley remained in a coma in "critical condition" at the hospital. For days, doctors conducted tests to see if Brumley was responsive, but there was no change.

"They are going to run three tests on him...to determine if he is still with us or not, if he passes even one then he is still with us, if he fails all of them, than legally he is gone," Gilbert posted on Facebook on March 8. "So today I am praying for one breath, just one!"

Three days later, Alexander confirmed Brumley did not take his own breath and he died later that day.

Alexander was shocked by how quickly Brumley's sinus infection turned deadly and hoped to share his story in hopes of preventing families, like hers, from facing similar fates.

"I think it is very important to express how serious a sinus infection can be, not to take them lightly or to blow them off," Alexander added.

The teen, a straight-A student who played football and the trumpet in band, is being remembered as a "goofball," who "loved helping people."

"He wanted to build houses, loved playing video games...he loved his mom and sister fiercely, and was their protector," Alexander said.

Nearly 400 people have donated to Brumley's page, raising more than $12,700 in just eight days.

"The love and support everyone has shown is overwhelming and so appreciated. Marquel was a very kind and loving person that will be missed terribly," Gilbert wrote in a recent update on the fundraising page.

Alexander added that the family is taking comfort in knowing Brumley was an organ donor, learning Thursday that he saved seven lives.