Fewer than 50 people in the United States have had brain flu. Doctors said there has not been much research on the condition.
Members of Banks' family said they are extremely worried.
"We didn’t know what the brain flu was. We’re, like, 'What's going on?' and, basically, it's fluid on the brain," Banks' sister, Shaunteh said.
Shaunteh said her brother started having flu-like symptoms on Nov. 11: a fever and a bad cough. She also said he felt weak.
Banks' family and friends were not too concerned at first but when the illness lingered for days and days, they took him to see a doctor.
Banks told his sister he was going to be fine.
Two weeks later, Banks thought he was still battling a bad case of the common flu but wanted to make sure, so relatives took him to another hospital.
He was admitted on Thanksgiving Day and that's when doctors told his family they believe he has brain flu. Banks later fell into a coma.
His sister said she hopes doctors can officially diagnose the problem and heal her brother.
"I just immediately thought, 'OMG, he’s dying.' Like, that’s just how serious we took it," she said.
Banks' family hopes a specialist can take a look at the case and figure out how to get him healthy again.