Lichaj had been struggling with a pelvic problem in recent weeks and suffered a recurrence of the injury on his return to the team against Wigan last weekend.
The USA international initially sustained the injury against Watford on January 30 and Forest had hoped a month of rest had resolved the issue, but Lichaj had to come off just before half-time during Saturday's 4-1 defeat at the City Ground.
The Sky Bet Championship club now fear the 25-year-old may require hernia surgery to remedy the problem - similar to that which Andy Reid underwent last week.
Like Reid, Lichaj would then be ruled out for at least a month while he recovers.
Forest are already having to cope without a host of senior players because of injury, including centre-half Kelvin Wilson and midfielders Reid, Henri Lansbury and David Vaughan, while Chris Cohen, Jack Hobbs and Dexter Blackstock will miss the remainder of the season.