The Spurs captain was named in the starting lineup to face Aston Villa but dropped out of the warm-up early and went straight down the tunnel.
He was replaced in the side by Kevin Danso, with Romero instead having to watch on from the bench as Spurs were beaten 2-1.
It is a busy run of fixtures ahead for Spurs, who are in Champions League action on Wednesday night away to Monaco, and any sort of spell on the sidelines for Romero would be a huge blow.
However, asked if Romero would be fit for the trip to Monaco, he added: "I don't know. He could be, he couldn't. I just don't know.
“Right now if I'm honest I had one focus. I went into the changing room, I just spoke to the players and prepared a little bit for the questions I'm going to have.
Jun'ai Byfield was the only defender on the bench against Aston Villa, though the 16-year-old is unlikely to be thrown into first-team action by Frank.
Should further issues be picked up in the centre of defence, it is likely Joao Palhinha or Archie Gray will have to slot in.
Destiny Udogie was not in the squad to face Aston Villa after picking up a knee issue while on international duty with Italy.