Ameobi was dismissed by referee Phil Dowd shortly after Daniel Sturridge found the net for the hosts to complete the turnaround following Newcastle's opener, which came via a Martin Skrtel own goal.
The Nigeria international, who is out of contract at the end of next month, was shown two yellow cards in quick succession by Dowd supposedly for dissent, however, Ameobi insists that he was merely pleading his case to the match official.
"You can't make up the way I was sent off. I still don't know why it happened," Ameobi told the club's official website following the first red card of his career.
"I was given a first yellow card for dissent, but for the second one I'm ready to take the restart when the referee has called me back.
"He told me to stop showing dissent, so I told him that I was allowed to plead my case. I asked him 'are you going to send me off for trying to plead my case for my team?' and he said 'yes'.
"I've asked a question and been sent off for that. I'm dumbfounded by it.
"People who know me know I don't swear and that I am not abusive.
"If this is my last game for Newcastle then it isn't the way I would have liked to go out. I'm quite upset by it.
"If it is my last game, I wanted to go out on a high and we were doing great for an hour.
"I'm disappointed in myself for putting myself in that situation in the first place, but in the heat of the moment when decisions aren't going your way you get frustrated.
"I've apologised to my team-mates and would like to apologise to the fans because they were here cheering every single one of us on."
Ameobi has made more than 400 appearances for Newcastle, scoring 79 goals.
