These symptoms are also the symptoms of carbon monoxide poisoning.
Have your furnace checked and consider that you may have an exhaust leak in your car.
You can't smell it or see carbon monoxide. Constant exposure to even small amounts does long term damage.
Try to correlate when the symptoms occured and what you did and what you were around in the 24 hours before the symptoms. The only treatments I know of is oxygen and hyperbaric treatments.
A DX can test for the CO in your blood but it is painful. They take a blood sample by sticking a syringe deep into your wrist to sample the arterial blood. Hurts like a bitch but it would be your only confirmation.
It was the only time in my life I ever experienced panic attacks.
Sorry to say that most DX don't think of it. It would have killed me if I hadn't figured it out myself.