Sometimes I have panic attacks (with heart palpitations, strained breathing, dizziness, etc.) and I don't feel anxious at all/nothing caused it. My therapist said it's just the brain's response to a chemical imbalance that makes your body think something bad is happening to you when nothing is triggering it at all. Usually I just do grounding techniques (deep breaths, counting, etc.) like normal and it goes away after a while. If chest pains happen often and you're worried about it you can also get an EKG to check on it which is what I did a few years ago. Hope this can help in some way!