The Rugby Football Union confirmed the flanker's injury and he spent Saturday night in Charing Cross hospital.
"Scans show evidence of a fracture to his right scapula," said an RFU spokesman.
Croft will see a specialist this week to determine the extent of the injury and what further action needs to be taken.
He is now likely to miss a host of important games with Leicester Tigers in a busy festive period, most notably the Aviva Premiership showdown with London Irish and the back-to-back Heineken Cup encounters with Perpignan.
The 25-year-old could still make England's Six Nations opener against Wales on February 4, but he faces a race to prove his fitness.