Blackwell said: "It was a foul on Kyle Walker but it wasn't given and then the shot hits Chris Morgan and wrong-foots Ian Bennett for the only goal."
He added: "Kyle has damaged ankle ligaments and could be out for up to six weeks - that's 11 serious injuries this season so far. I have never had anything like it in my career.
"I was hoping to get Jamie Ward (broken wrist) and Lee Williamson (back) back for this game but they weren't right in training and if I risk them now I'll lose them until Christmas and we can't afford to do that.
"(Nick) Montgomery (knee), (Richard) Cresswell (ribs), Ward, Williamson, (Gary) Naysmith, (Derek) Geary (both knee) - they'll all be back hopefully by the end of the month and things will start to look different then."