Hello and welcome to the forum.
Colds, sore throats, and respiratory infections are super common and myocarditis is not...so this is the good news (ie the chance that you have myocarditis is low). However, the risk of course is not zero. If you are experiencing new symptoms (which is sounds like you are) and you are worried, I would do the following:
1. See your PCP
2. Tests to start with include an ECG. If still concerned, an echocardiogram would be reasonable. Lab tests that look for release of proteins from the heart (called troponins) would also be reasonable should the concern for myocaridits be high.
3. If 1+2 are reassuring but you continue to experience funny heart beats/skipped beats, etc and nothing is picked up on the ECG, I'd consider a 48 hour Holter monitor.
Best of luck,
Thanks very much doctor. I shall follow these suggestions.
With warmest regards,