Owen Haggerty, 22, was just a day away from returning home to Scotland when he tried to stop a street brawl on the Middle Eastern island last month.
Distraught mum Kirsty Reynolds, 41, from Johnstone, Renfrewshire, said he had remained at the scene to check on an injured victim when he was taken away by police.
He was held in a detention centre until yesterday - when a judge ordered he be sent to the tough Hidd Prison for three months. Now, Owen's family have pleaded with Royal Navy chiefs, politicians and the foreign office to step in to help Owen.
And they have revealed he was not even allowed to defend himself in court before being jailed.
The mum of three told how Owen has been left "mentally drained after already being held for five weeks.
The beautician said: "I had a video call with Owen today.
"I saw his face and he's mentally drained. He said on the phone, 'Mum, I can't do it anymore'.
"His big brother flew over there as we thought he was going to be released today but the judge didn't even let our lawyer speak. It was all over in seconds.
"They have given him three months and are moving him from the detention centre he's in to the prison now.
"Owen has never been in any trouble at all in his life.
"Anyone who knows him knows he's not that type of person. I've been in tears all day."
Owen, an able seaman, was on his first deployment in Bahrain when the incident happened on February 14.
Kirsty, who has seen a case file on the incident, says it involved an Egyptian couple who have since returned home.
She said police found her son at the scene, who had been trying to help, and had tried to return Owen to an American naval base before taking him to jail.
Kirsty explained: "He stayed there to try and make sure everything was OK because that's the type of person he is and they've pulled him in.
"They examined him and he had no marks on him - nothing.
"Owen told me he was shown CCTV and it...