Epstein led Illinois in rushing on Saturday (45 yards) against Akron before leaving the game with the injury.
Epstein posted a message on his Twitter account about his road to recovery.
Epstein has played 13 games for Illinois over three seasons. He has total 947 yards, including 802 on the ground and scored seven touchdowns.
Epstein led Illinois in rushing yards (346) and yards per carry (6.1) as a true freshman in 2017 and tied for the team lead in touchdowns (4).
He became the fifth true freshman in Illinois program history to lead the team in rushing yards.
The Ft. Lauderdale, Florida, native was a three-star recruit out of national power St. Thomas Aquinas. He was a top-100 running back in the nation and the 2016 Sun Sentinel All-Broward Football Player of the Year.