Following Aaron Mclean's arrival at City last week, Parkinson has moved to bring in loan trio Adam Reach, Kyle Bennett and Chris Atkinson over the past couple of days.
With Mclean brought in to take the place of Nahki Wells after his move to Huddersfield Town, Reach was borrowed from Middlesbrough this Thursday to replace the injury-hit Kyel Reid on the left wing.
On Friday, Bennett came in from Doncaster Rovers to join Aston Villa loanee Jordan Graham and Garry Thompson as options for Parkinson down City's right flank. Central midfielder Atkinson arrived later the same day from Huddersfield following Jason Kennedy's loan move out of the Coral Windows Stadium back to Rochdale.
Parkinson said: "We felt a bit of a change in the squad was necessary and that bringing in a few new faces will give the place a bit of a lift.
"We are still looking for a left back to add to what we have now. We haven't been able to get one in as of yet for a number of reasons but we are still looking.
"Kyle (Bennett) is quick and has good experience of this division. Jordan (Graham) came in at a time when we'd sold Nahki and we were struggling with numbers due to injuries.
"We needed an impact player off the bench.
"Jordan has been unlucky so far though because Reidy has come off injured in both his games meaning we've had to bring on a left winger instead.
"He is only a young player and we have to be careful what expectations we put on him. Kyle has a lot more experience with Doncaster and on loan at Crawley earlier this season.
"Chris (Atkinson) comes in as a player with good energy to his game and someone who has played a lot of first-team football this year.
"With Jason (Kennedy) going out, we felt it was important to get another midfielder into the building."