Rays manager Kevin Cash said that Franco underwent tests, which were negative, and that he anticipates the 20-year-old will be back in the lineup "within a game or two" as long as he continues to improve.
"He got a good night's sleep," Cash said before the team's 5-3 win. "He woke up, went to see the doctor. Everything checked out. He's in a much better place right now."
Franco extended his on-base streak to 33 games with a seventh-inning walk Thursday night against Boston but left after the at-bat with a headache. He tied Hall of Famers Mel Ott and Arky Vaughan for the third-longest streak by a player under 21.
Franco was checked by a trainer after pointing toward his head several times earlier in the plate appearance. He was tagged out by Red Sox catcher Christian Vázquez trying to score from third on a grounder Wednesday night.
"We don't know if it was the play the night before or just a headache popped up," Cash said. "But whatever it was, it was enough to make enough sense to get him out of the ballgame."