TAMPA (FOX 13) - Wiregrass High School freshman Jacob Chellew remembers trying to make the tackle.
"I hit him like this," he said, describing going for his opponent's waist. "But his knee hit me and I fell back."
He doesn't remember anything more until the ambulance.
"The first thing I remember is... looking around into the bright lights," he said.
He had a concussion, which for a week prevented him from getting through an entire school day.
"My eyes would get tired really quickly," he said. "The lights would start to bother me."
His parents had a decision to make.
"If we had been told that there was significant risk, or going back was not a good thing, we definitely would have ended his football career," said his father, Dan Chellew.
Jacob is one of the estimated 300,000 high school athletes who every year get brain injuries playing sports, double the number since 2005.
Doctors like Byron Moran of USF Health say they don't yet know what risks people like Jacob face long term, except that those who make it to the pros often wind up with CTE, or long-term brain damage.
"We know what the outcome can be, but we don't know what risk factors lead to that. Is it purely the number of injuries? Is it the timing of those injuries? Is it the lack of recovery between injuries?" Dr. Moran said.
Dr. Moran works at USF's new concussion center on N. Dale Mabry, and says the center is the first in Tampa Bay that can provide comprehensive concussion care while also researching the nagging questions.
"Because of that vast void of knowledge that we have to be aware of, it's hard to give people a hundred percent certainty (on their injury," Moran said.
But it's not just football. Studies argue female athletes are 12 percent more likely to get concussions.
"Another concussion will probably end it. It's not worth long-term damage," Jacob said.