The Spurs goal machine missed seven weeks from the same injury in September 2016 and a month again earlier this season, and their medical team believe this incident is similar to the former in severity.
Given the delay for a diagnosis, it looks highly unlikely that the 35-goal striker will be fit for Spurs' FA Cup quarter-final at Swansea on Saturday, while his involvement in next week's worldwide break also looks doubtful with England set to face Holland and Italy in friendlies.
The 24-year-old was pictured with his foot in a brace and using crutches when out in Essex on Monday.
A long lay-off will also seriously hurt Spurs who have already lost him for Saturday's FA Cup quarter-final at Swansea.
With the World Cup in Russian Federation now less than 100 days away, the FA will not want Kane rushed back from his injury by Spurs.
Spurs have a league clash against Newcastle to reschedule, while their trip to Brighton on Friday April 20 would also get postponed if they reach the FA Cup's last four.
He will then miss the semi-finals if they win and four league fixtures after the global break, a potential top four decider against Chelsea and further clashes with Stoke, Manchester City and Brighton.
The injury occurred after a collision with Bournemouth goalkeeper Asmir Begovic in the first half at Dean Court.