Peterborough United defender Mark Little is braced for a spell on the sidelines as he tries to determine the extent of a mystery groin injury.
The 23-year-old lasted 51 minutes of Saturday's 1-1 draw at Birmingham City.
"It comes and goes. I couldn't get through it anymore on Saturday," he told BBC Radio Cambridgeshire.
"I'll see a specialist. We've been treating it here but it's just not going away. At this point we've got no idea what the problem is."
Posh boss Darren Ferguson had initially suspected the right-back could be suffering from a hernia problem but Little says the issue seems to be more complicated than first thought.
"It keeps moving around. That's why it's an ongoing thing," he explained. "I can get through it and then can't get through it.
"That's no good when the gaffer's picking his team. So we're just going to get it sorted out now and find out what it is.
"I was gutted it was the Blues game as well. It's my hometown and probably the nearest ground to my house. But that's football."
The result at St Andrew's keeps the Championship newcomers in 11th place, but continued a worrying trend of conceding first in matches, a run which stretches back across Posh's last six games.
"We need to know that we're going out on the pitch to get three points and genuinely believe it," said Little.
"Rather than playing the game and thinking, 'we're doing alright', we need to realise we're not doing alright and we should be beating these teams.
"We should be 2-0 up in the first half rather than waiting to come back into games as we do all the time."