The left-back was forced off in the second half of Saturday’s 2-0 defeat at home to Sunderland and is a doubt for this weekend’s trip to West Ham.
“We’re going to find out a bit more in the next two days,” manager Roberto Martinez told evertonfc.com.
“It was really, really painful 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 30-year-old, traditionally ultra-consistent with his fitness, has had more than his fair share of injuries this season having missed matches in November with a hamstring problem and a thigh and knee injuries sidelining him in February and March.
Baines was replaced by Luke Garbutt on Saturday and a late run of games in the side may help persuade the 21-year-old to stay on at Goodison Park as his contract expires in the summer.