The left-back was substituted in the Toffees’ game with Sunderland at the weekend and replaced by England Under-21s ace Luke Garbutt.
U21s left-back Luke Garbutt has been Baines' understudy at Everton this season
And the 30-year-old could now miss Everton’s remaining two Premier League games this season.
"We're going to find out a bit more in the next two days," revealed Blues boss Roberto Martinez on evertonfc.com
"It was really, really painful and in an area that has been a bit of a problem for Leighton.
"We'll get more clarity over the next 48 hours and clearly we'll address it once we get that information from the specialist."
The former Wigan Athletic player has endured something of a frustrating season, after missing games in November with a hamstring injury and then a knee problem saw him sidelined in February and March.
Garbutt was his replacement during that spell and the 21-year-old will now be hoping for a chance to finish the term in the team ahead of this summer’s European Championship Finals in Czech Republic.
