RampantBadger said see your doctor, not undergo heart surgery. You aren't going to be killed by asking your doctor for advice. And I agree with him, a heart rate of 30 could indicate serious underlying pathology.
Alternatively, if you are very fit and your heart rate has been that low since you were in your 20s it could be normal for you. I'd definitely still get it checked out though.
EDIT: I highly doubt it has anything to do with garlic. If garlic does cause your blood pressure to decrease, your heart rate would either remain the same or increase (as a compensatory measure). It certainly wouldn't cause your heart rate to drastically decrease.
If both your blood pressure and heart rate decreased in an acute time-frame you wouldn't be able to perfuse your organs, which is obviously very serious.