Mancini has been out injured since the end of January but turned out for Belgium on Tuesday night against boss Mancini's wishes.
Mancini said: "I asked him to stay here for treatment. I didn't want him to play because it was a risk.
"For us the next two months are really important. He said the manager had called him and he should go. It is right that he should go and meet with the Belgium medical people, but then he should come back.
"It was important Vinny should work here and prepare for the next game - and the next two months. I expected he wouldn't play and that he would be back after one or two days.
"Instead, he played for 90 minutes against Macedonia and now we don't know his condition.
"The calf is a difficult injury and we don't know if he will be OK or not."