Could Chest Discomfort Starting 3-4 Days After The Second COVID Vaccine Shot Be Myocarditis?

Me and my wife recently got our second covid vaccine shot and about 3-4 days later she started feeling a little chest discomfort. She describes it as tightness or constraint. She suspects that it is myocarditis. She doesn t have any other symptoms and we are just wondering if it could be that and what the symptom progression is how long it wouldd last if it was? She s not in pain but is really scared