The Sun reports that Gerrard, who has been put on an antibiotic drip, will discover the extent of his latest setback tomorrow.
The 31-year-old has been struggling with injury problems this year.
He said: “There were times when I was as low as I have ever been.
“I think it’s only natural that you have doubts and different things do cross your mind from time to time.”
Kop boss Kenny Dalglish said: “Will he be fit for England v Spain? I haven’t got a clue.
“It’s nothing to do with any injuries before, it’s an infection. I suppose it’s like having an abscess on your mouth.”
