The Blues were booed off at the end of both halves at St Andrew's and Clark admitted he has no idea why their performances at home have been so bad this season.
The latest defeat saw Town leave with three points, giving their new boss Mick McCarthy a boost on his first day in charge, and left Clark pondering what to do after a fourth winless game on home turf.
"We're creating a negative attitude around the stadium with our first-half performances," Clark said.
"We're starting (home) games - certainly Barnsley, Huddersfield and today - so flat that the crowd become apprehensive and a bit bored to be honest with you because they're not getting dished up any quality or drive.
"Then they do it in the second half. But why? Why not do it from the first whistle?
"I like continuity and I try to keep the same team but, with the exception of one or two, there aren't many putting down markers week in, week out to hold down a regular place in the team.
"I hate changing the team around but I've got to have players who are playing consistently well week in, week out home and away."