He was discharged later that day but was taken back to hospital following further seizures.
Mr Hillman woke in hospital on October 31 unable to speak or move the right side of his body.
He was diagnosed with meningoencephalitis after receiving a lumbar puncture which revealed an abnormal cerebrospinal fluid.
Upon further review, his condition was upgraded to disseminated encephalomyelitis.
On November 1 a borehole was put into his head to relieve pressure, but he remained unresponsive.
Life support was withdrawn on November 6.
A post mortem examination showed the cause of death was encephalitis, which was probably viral, the report said.
Mr Hillman's mother, Annette Thompson, expressed concerns about what she perceived to be a lack of tests done early on, wondering why her son was sent home, given his obvious symptoms.
However, evidence given by Doctor Richard Dinsdale showed that doctors did not think there were any ways in which Mr Hillman's care could have been improved.
Coroner Ian Roderick Smith found Hillman died as a result of encephalitis, "probably of a viral aetiological undetermined agent".
He said while he "bowed to the expert knowledge" of medical personnel, he thought it would have been appropriate to have completed an MRI scan at the earliest opportunity.
"It should also in my view be, that Mr Hillman to have remained at hospital from the date of his initial admission until all testing had been completed, to establish a correct and final diagnosis.
"However, having said that, it does not appear that the chances of Mr Hillman's recovery were, from an early stage, very remote."
