It depends which arrhythmia it is. There are many types. Yes, stress can cause certain arrhythmias.
The easy question first - Yep, stess has been known to bring on "weird" beats.
As to what an arrythmia feels like, that varies from person to person. Here are some of the feelings I've seen associated with an arrythmia:
heart skipping
heart tumbling
a weird feeling in your throat
chest discomfort associated with palpitations (sensation of one's own heartbeat)
flip-flopping
a drop feeling, like in an an elevator
racing heart
pounding heart
Sometimes, anxiety can cause the same sensations....
connie