The star striker is still unable to eat properly after suffering a fractured cheekbone and eye socket during Saturday’s 2-0 Championship defeat at Middlesbrough.
Powell says the nature of the latest setback for the injury-plagued 26-year-old, who took an accidental kick in the face, means a no-risk policy towards his recovery programme.
“It’s obviously a serious one, and because we’re talking about the area surrounding his eye, the medics must be absolutely sure he’s right,” said the manager, whose side head to Wigan Athletic this Saturday.
“He may be able to do some fitness work fairly soon, but he will clearly need to avoid contact situations.
“It’s just really bad luck, but we have to make sure he is right before he returns, both for his sake and that of the club.
"Now I'm just hoping that he'll be able to play some games again before the end of the season."
Powell, who says he may now try to bring in two new strikers, added: “We all feel for James.
“We had been working carefully to reintroduce him after his calf injury.
“Two goals in the last four league games showed he was getting there.
“And we were pleased at the development of his partnership with Nahki Wells.
“They were certainly getting there.”
Powell said he has had no contact from Cardiff City amid reports the Welsh club are interested in defender Lee Peltier, who has been on the fringes at Town.