Infectious myocarditis is relatively rare, and it is very startling when it occurs, maybe especially in young people (but older folks are pretty darned shocked, too). Each case is individual, and unfortunately we are only patients like you--not doctors. You simply must write down your questions and concerns in an organized way and *ask* your doctors, who know your history and have examined and treated you, about this. Keep at them until you get answers that mostly satisfy you.
On the other hand, please understand that the fact is that your cardiac cath, your Holter, and your stress tests were normal. That means that at this point, your heart is strong enough to handle normal physical exertion. This is really very encouraging.