(CNN) -- Calvino Inman had just stepped out of the shower one evening in May when a glimpse of his reflection in the mirror caused him to panic. "I looked up and saw myself, and I thought I was going to die," says the 15-year-old from Rockwood, Tennessee. His eyes were streaming tears of blood. 

Doctors are still searching for a medical reason for Calvino Inman's tears of blood. 

Inman's mother, Tammy Mynatt, says she immediately rushed him to the emergency room, but by the time they arrived, the bleeding had stopped. Doctors couldn't see what the family was trying to explain. They returned home completely perplexed. When the bloody tears returned a few days later while Inman was on a camping trip, he was rushed back to the hospital. 

Mynatt hoped that once doctors finally witnessed the phenomenon, there would be answers. But that wasn't the case. "The people at the hospital said they had never seen anything like it," Mynatt recalls. She says her son underwent an MRI, a CT scan and an ultrasound, but none of the tests had abnormal results. "'We don't know how to stop it,'" Mynatt remembers being told by doctors. "It just has to run its course." 

Dr. Barrett G. Haik, director of the University of Tennessee's Hamilton Eye Institute, says there is an answer, sort of. He says "crying blood," a condition called haemolacria, is common in people who have experienced extreme trauma or who have recently had a serious head injury. But a case such as Inman's is still a medical mystery. "What's really rare is to have a child like this," Haik says. "Only once every several years do you see someone with no obvious cause." Watch more on the teen who cried blood » 
How old is he?
 "I looked up and saw myself, and I thought I was going to die," says the 15-year-old