Johnson was examined Wednesday in Florida. There was no structural damage found and he will rejoin the Marlins on Friday for a series in Washington, but the team has not decided when he might pitch again.
Johnson stopped a bullpen session early on Tuesday because of discomfort in his back.
Manager Edwin Rodriguez hadn't heard of Johnson's shoulder problems until Tuesday. Johnson's back had been bothering him for about two or three weeks.
Rodriguez says Johnson could start next Wednesday. Johnson could also be shut down for the season.
Johnson is 11-6 with a 2.30 ERA. He is 2-3 with a 3.50 ERA since the All-Star break.
Right-hander Ricky Nolasco had knee surgery on Wednesday and needs four to six weeks of recovery. Nolasco is on the 60-day disabled list and had earlier been ruled out for the rest of the season.
Rodriguez says Ramirez could pinch-hit Wednesday night.
Ramirez was hit by a pitch on Monday and complained of pain in Tuesday's game. He was 0-for-5 in Tuesday in an 8-7 loss to the Phillies. He is batting .300 with 21 home runs and 75 RBIs.