Bradley Lowery will not be able to lead out Sunderland for the team's game against Boro tonight because he is unwell.
The Blackhall Colliery youngster, who is due to turn six next month, has been treated for neuroblastoma for the second time after the cancer returned last year.
He was due to be mascot once again for his favourite team Sunderland as its squad plays Middlesbrough this evening, but his appearance has been cancelled because he is ill.
His parents Gemma and Carl were told before Christmas that the medication he had been given had not stopped the disease from progressing and they have been working hard with the help of supporters to give Bradley as many good memories as possible.
Today, Gemma has shared a post on the Bradley Lowery's Fight Against Neuroblastoma Facebook page, telling of how doctors think the pain he has been suffering could be a sign his cancer could be progressing.
She has written: "Bradley is not good.
"He has been in horrendous pain with his leg since yesterday to the point he couldn't move in bed last night.
"We have had him to the hospital today and they have give him a x-Ray but it didn't show anything.
"The doctor's gut feeling is that it is his cancer progressing but we need to wait and watch for a few days to see what happens.
"Bradley was due to be mascot at the Riverside tonight but he is not well enough to go so we have had to cancel it.
"I am hoping and praying that it is nothing serious and he starts to improve as I'm not ready for this to happen yet 💔💔"
Sunderland are due to play Middlesbrough at the Riverside Stadium this evening, with a 7.45pm kick off.