Waddle, who missed practice Wednesday and Thursday, returned to practice Friday for the first time since suffering the injury.
"I'm feeling good," Waddle said. "Came out here, did some stuff today. Go back, do some more tests and stuff like that and see how it feels later on in the day and we'll see where we go from here."
Waddle said he did everything in practice Friday but was not sure whether he would play Sunday against the Atlanta Falcons at Wembley Stadium. He is officially listed as questionable.
Tight end Brandon Pettigrew (foot) is doubtful, along with running back Reggie Bush (ankle). Bush has been dealing with an ankle sprain the past three weeks and after saying he would play Tuesday and practicing Wednesday, he did not practice on either Thursday or Friday. Now, with a doubtful status for Sunday, it appears he may not play at Wembley after all.
Wide receiver Calvin Johnson is questionable but has practiced all three days this week on a limited basis.
Waddle's concussion became a point of contention with the Lions on Thursday, when there was some confusion as to how his concussion protocol was handled. Waddle suffered the concussion on the extra point following the Lions' go-ahead score, but then played in the game's final play, a kneel-down.
He also said he did not inform doctors of his condition.
"I was a little woozy but I didn't really know what was happening," Waddle said. "I didn't realize I had a concussion. I thought I got shook up a little bit but I thought I was good, you know."
Lions coach Jim Caldwell said Thursday the Lions knew when it occurred and "what happened within the context of it." He then said the team knew Waddle hit his head on the ground but that doctors did not think he had a concussion.
"Obviously he went back on the field the final snap," Caldwell said. "We knew it was only one snap. The doctors reviewed him, took a look at him. It wasn't one of those situations where we felt he had to go into the locker room right away.
"But they did know he banged it when he came off."
Later on Thursday, the Lions released a statement saying the NFL's medical observer contacted team doctors during the final play to suggest an examination of Waddle, not beforehand.
"Coach Caldwell's response to the media [Thursday] regarding when the injury occurred and Waddle being on the field for the final kneel-down play was based on information given to him by the medical staff after the game," the statement read. "The Lions' medical staff informed Coach Caldwell after the game that Waddle had not reported any injury to them until after the game, which led to further examination. The team's medical staff also informed Coach Caldwell that the NFL medical observer, who observes the game from the press box, did contact the team's medical staff during the final play to suggest an examination of Waddle. The exam was done in the locker room after the game, and the concussion protocol was immediately initiated.
"Coach Caldwell's comments earlier today reflect that no one on the medical or coaching staff believed he had sustained an injury that would have necessitated Waddle being removed from the game or taken to the locker room prior to the end of the game."
On Friday, Caldwell said doctors' protocol will determine whether or not Waddle will play Sunday.
"You know it'll be doctors' protocol that'll make that determination as well as with the rest of the guys that are on that injury report," Caldwell said. "If not, obviously we have had a couple guys that have had some playing experience there, fortunately. It's not a brand new experience for us to work with those particular individuals in both [Garrett] Reynolds and [Cornelius] Lucas, who play that spot."
Caldwell did not indicate if Lucas or Reynolds would end up starting if that happened.