He has been restricted from baseball activities since Thursday.

"That's why the doctors tell me to just take a week, just rest, don't let your heart get too much heart rate,'' he said. "If it goes away, just go back to work.''

According to Johns Hopkins Medicine, myocarditis is an inflammation of the heart muscle that is usually due to a viral infection. The inflammation can lead to arrhythmias, cardiomyopathy or heart failure.

Rodriguez said his doctors told him that 10-20% of people who have had COVID-19 also have been diagnosed with myocarditis.

He said the experience was eye-opening, but that having a mother who is a nurse has helped put his mind at ease.

"That's the most important part of your body, so when you hear that, the first time I hear it was kind of scared a little,'' Rodriguez said. "Now that I know what it is it's still scary, but I know exactly what it is. Just talk to my mom, talk to my wife, they know what I have and everything. Now we just gotta take the rest. That's hard, but you gotta take a rest.''

Rodriguez previously said that his bout with the coronavirus had left him feeling "100 years old" and that it took him about 10 days before he was able to do any light throwing. He said he's currently not experiencing any COVID-19 related symptoms.

With David Price gone to Los Angeles as part of the Mookie Betts trade and ace Chris Sale missing the season following Tommy John surgery, Rodriguez had been in line to be Boston's Opening Day starter. He posted career-best numbers in 2019 with 19 wins and a 3.81 ERA. But with him sidelined, those duties fell to Nathan Eovaldi.

Rodriguez is unsure of how long it will take for him to be ready to pitch in a game.

"As soon as I throw the first ball, I'll let you know. I need to know how my shoulder feels,'' he said. "It could be more, it could be less. It depends how it feels the first time I throw the ball."