The headaches have subsided and Avila was cleared to play Thursday morning by team doctors.
"I'm good to go," he said with a smile. "[I feel] much better. Everything was better across the board. I just feel better mentally. I feel more normal. Everything's good, no more headaches, nothing like that. Jaw's going to be sore probably for a few more days, but a little pain's not going to hurt me."
Manager Jim Leyland elected to keep Avila out of the starting lineup for one more day as a precaution, but said he would be available off the bench in the finale against the A's.
Avila was in an especially good mood as he joked with the media and continued his season-long trash talking to Gerald Laird, who started the past four games in Avila's place.
"I'll tell him to enjoy his last few starts," Avila said.
The 25-year-old even shared some messages he received from friends following the incident.
"I got a few phone calls and texts like, 'What are you doing running into a tree?' And stuff like that," Avila said.
Avila also said he understood the magnitude of the situation. He's seen the replay and cringed watching Fielder's thick elbow crash into his skull. And he's seen what's happened to players like Twins first baseman Justin Morneau, who suffered a concussion in 2010 and is just now getting back to his old self.
"Obviously hearing stories from guys like Morneau and talking to them over the last couple of years and seeing what he's gone through ... that's something I didn't want, especially in my position knowing that I'm going to get hit in the head a few times," Avila said.
He knows it could have been worse. He's just thankful it wasn't.
"It's something that in my position could cut my career short," Avila said. "Obviously I had to think about myself and career and quality of life after that, so I had to make sure I was right before I got back out there."