The 22-year-old, Rangers' leading goalscorer, revealed he faces an uncertain future after making his third appearance for Forest at Sheffield United on Monday. Both former QPR manager Paulo Sousa and team-mate Rowan Vine have spoken publicly of their shock at the club's decision to let him go.
Blackstock said: "The manager at QPR has said he had no input in the decision but I wasn't aware of that at the time because the deal was done through agents.
"I didn't know who had given clearance for the deal to go through until I had actually signed. Managers should make decisions like that, but it doesn't always work that way.
"I wouldn't say it's over for me at QPR. As it stands at the moment I'm here on a six-match loan and then I go back to QPR. They are my club. I've got a year left down there and I've got to go back.
"Whether there's a future for me there I don't know - that's another story. I think from the outside looking in everyone can see what is happening. I was by far and away the top goalscorer there this season on 12 - I think my closest challenger has five - and the manager and players didn't want me to go."