Quashie joined Birmingham last month after impressing on a trail spell with the Midlands club and has so far made only two starts for the club and been sent off in one of those.
The 30-year-old Scottish international will stay until December 28th.
"Hopefully he's going to get much, much sharper and then we can look at extending it further.
"Nigel knows that he's missed an awful lot of football and he's now trying to impress. He's given us a fantastic contribution.
"It's about getting games under his belt - and there's not any reason for us to rush into a long-term agreement."