Byrd, who was in a summer-long contract dispute with the Bills, said Monday that "it hurt" to watch the game from the sideline.
"It was a really weird feeling. To be honest, it hurt," Byrd said. "It's not a good feeling to watch a game like that."
Diagnosed with plantar fasciitis in both feet, Byrd said he played through the condition last season, starting all 16 games.
"What you saw me do last season was with it," Byrd said. "It's something that's just been lingering. What you saw me do for a majority of the season was with this."
Byrd had five interceptions last season and forced a career-high four fumbles.
However, he remains limited in practice and was declared inactive for Sunday's game.
"I'm just waiting on my feet, honestly," Byrd said. "Whenever they get ready and get right, that's when I'll be able to go out there. I have to be 100 percent to be out there and be ready to go."
Byrd said his treatment plan for his feet includes orthotic inserts in his shoes, creams and stretching. He did not know when he'll be able to return to playing.
"I can't predict the future," he said.