Jones lost consciousness following a clash of heads with Walters.
He was taken to hospital following the first-half incident, although he was able to return to the ground and link up with the rest of his team-mates after United's 2-1 defeat.
"Phil is okay," said United manager David Moyes. "He has been checked at the hospital.
"He was out for a little while. I saw him falling back and his head going back on the grass. He got up but when we went to treat him he lost consciousness for a while.
"The medical team did all the right things. They got him to hospital but he is fine. It looks like concussion. He should be okay."