Doncaster Rovers sent the England goalkeeper back to the DW only days into his loan arrangement.
The 30-year-old, for whom back complaints have been a recurring issue during his career, suffered a spasm and returned to the DW Stadium for treatment instead of playing in the midweek defeat at Blackpool.
"We were ready to see Chris in action on Tuesday but unfortunately he has had a little bit of a setback," said Martinez.
"It is nothing too serious and we should see him back in the next six to seven days.
"We are talking about a minor problem and we will solve it pretty quickly."