Source: 'No idea' when Jonathan Stewart will be back

Jonathan Stewart remains on the PUP list at Panthers training camp as a source with knowledge of the situation tells CBSSports.com there's "no idea" when he'll be ready to return. 

Stewart had surgery on both of his ankles this offseason, one in January, one in February. According to the source, doctors don't know why one ankle healed properly while the other, his right ankle, is still giving him trouble. He continues to rehab in hopes of getting back on the field but the situation remains fluid.

"It could be any day or it could carry on into the regular season," the source said. 

DeAngelo Williams has taken most of the first-team reps with the offense while Stewart sits out.