Simon Davey admits he does not feel 'justice was done' after Barnsley striker Iain Hume suffered a fractured skull against Sheffield United.
Hume has been moved to a hospital ward from a high dependency unit after undergoing an emergency operation on the injury he sustained last Saturday.
The Canadian international was hurt after being elbowed by Chris Morgan, with the Blades defender receiving a yellow card for the challenge.
Davey remains unhappy with referee Andy D'Urso and is disappointed the Football Association are unable to take any further action.
"He was our £1.2million record signing this summer and is our top goalscorer, along with Jon Macken," Davey told Sky Sports News.
"How long are we going to miss him for? We could be having him out for the rest of the season, we don't know, but it doesn't seem that justice was done.
"There was no sending-off, apparently the FA can't make any charges against the club or player because he was given a yellow card, and we lost the game and lose a player for God knows how long who is a very important and integral part of our squad."
The Tykes manager confirmed the Championship club are exploring other avenues regarding some form of action being taken in response to the incident.
He added: "The board are discussing it with the legal people on how to take it further and they are taking advice on that.
"But that's at boardroom level and for me the most important thing is the player is well, he gets back, he recovers and everything with his family is okay.
"We have lost a player, but there is more to life than football. It's lucky that the player is in hospital and not the mortuary. If he'd gone to sleep, and if his father-in-law and wife hadn't been so caring, we might have lost him.
"That's why I'm so angry that it wasn't taken a bit more seriously."
Davey is still disappointed that Hume did not receive sufficient protection from D'Urso after being given a buffeting throughout the first half of the 2-1 defeat.
"I was unhappy at the time when it happened," continued Davey. "The game is a physical game and things go in a game that we've all seen and we've been involved in, but for me the referee didn't take action and that was what most upset me.
"At half-time, I tried to go to see the referee and asked him, 'Did that warrant a yellow card?' because I felt it warranted a red card and he said it warranted a yellow card.
"We were a bit concerned as Iain mentioned himself in the first half that he'd had a lot of treatment from the opposition and had been caught with an elbow 10 minutes previous to the one which fractured his skull.
"We felt we weren't getting any protection, culminating in a player landing in hospital - that was my most frustrating part that I didn't feel we were getting the right treatment as a club and the right protection."