Clayton is scheduled to undergo an MRI on Tuesday to help determine whether he will be able to play again this season, according to the source.
Crayton caught three passes for 105 yards and scored his first touchdown of the season in the Chargers' 35-14 win on Monday night. He has 28 catches for 514 yards this season.
If Crayton is out for an extended period, questions about the Chargers' depth at receiver could be answered by the return of receiver Vincent Jackson, who will be eligible to play for the first time this season on Sunday night.
Jackson rejoined the Chargers late last month after a lengthy holdout, in which he unsuccessfully sought a trade. He spent the Chargers' last three games on the sidelines, as he had been placed on the team's restricted list during the holdout.