Suggest Treatment For Tightness In Chest Area And Anxiety

My son has been experiencing what we thought has been anxiety symptoms, but we are beginning to think there is something more going on. He first experiences tightness in his chest, followed by a feeling of what he describes as out of body . He paces a lot because he says this helps, but I m not sure if it helps or it is nervousness or a symptom of something else. His heart races a little, but not to extreme and it comes and goes with at various times of day. It started out mainly at night when he tried to rest. Progressed so that it is almost happening daily. He is always concerned about when the next episode will occur now. He has been to a cardiologist and that has checked out fine. No other health problems except cholesterol. I m wondering if he could be experiencing a partial seizure? We need advice. Please help!!