The England international has not played for the club since damaging his heel on the final day of last season, and will now continue to seek specialist advice on his latest injury setback.
It was thought that he had suffered an Achilles problem, but West Ham confirmed on Friday that the issue is with his plantar fascia.
And while boss Sam Allardyce has moved to play down fears that he could require surgery, he is not putting a timescale on the striker's return.
"It's the same type of injury (to the heel problem) but in a different area," Allardyce told the club's official website.
"It is not an Achilles injury, as has been suggested, but instead it involves the band of tissue which runs under the foot.
"According to the specialist, the chance of a recurrence of that type of injury is about four per cent but unfortunately for Andy, he was one of the unlucky ones.
"We had been very cautious, very patient with him along the way and it's sad this has happened for him as well as us.
"He doesn't need an operation but we need to give the foot time to re-heal, continue the rehab and get him back in training again."
Carroll scored seven times in the Premier League for West Ham last season while on loan from Liverpool, before making his switch permanent in the close-season.
