The teenage winger, who has scored nine goals this season and was linked with a host of Premier League clubs in January, limped out of Saints' 1-1 draw at Charlton before the international break.
Chamberlain has been ruled out of Saturday's clash with MK Dons and could also miss the return fixture against the Addicks as well as matches against Leyton Orient and Rochdale.
But manager Nigel Adkins is hopeful he will be back to play a big role in the promotion run-in.
"Alex saw a consultant on Wednesday because he went over on his ankle," Adkins told the club's official website.
"Obviously he is still a young boy, only 17, and we have to make sure we get this one right so we will be very protective of him. We will shut him down totally and then reassess him in a week or two."
Source: PA
Source: PA