Allen suffered the injury at home in the win against Hull City in the Championship midway through September, having to be replaced just after a half hour.
The 32-year-old missed every game the Swans played in October, a run that includes five wins and a heavy loss to Burnley.
Allen is set to consult a specialist today regarding his hamstring injury in a bid to find out when he can expect to return to the pitch.
The Wales international will look to book a seat on the plane to Qatar after the Dragons qualified for the World Cup for the first time since 1958.
Wales manager Rob Page made it clear to his squad earlier that they need to be playing regularly to be in contention to make the final 26 who will travel to Qatar.
Allen has made nine appearances in all competitions for the Swans, earning one booking in the process, but has missed their last six Championship games.
Wales will lock horns with England, Iran and the United States in Group B, with the Americans set to be their first opponents in only their World Cup finals second appearance.
