Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I cannot tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
A possible consideration for the “rush feeling” that you are experiencing is that it may be a type of aura that is associated with migraine headaches. Auras present in many different ways, and may consist of visual, sensory, language, or motor disturbances. Other auras described include transient abdominal symptoms, periods of disturbed mentation, déjà vu experiences, and other bizarre symptoms. If you have a history of migraine headaches, these symptoms may precede or accompany your headache. However, there is also an entity known as migraine aura without headache in which the individual may have only the aura symptoms and no headache.
Seizures can also present in a variety of ways, and certain seizures known as simple partial seizures may present without any alteration in consciousness. The individual may experience unusual feelings or sensations that may be difficult to describe. These can include somatosensory, motor, autonomic, or psychic symptoms. They may be short in duration, lasting seconds to minutes.
If your symptoms are associated with feeling faint, or nearly passing out, or if you are having these symptoms in response to a certain triggering event, another consideration is that your symptoms may represent a vasovagal response. Vasovagal refers to the vagus nerve, which among its roles includes supplying parasympathetic nerve fibers to the heart. Stimulation of the vagus nerve can cause slowing of the heart rate and vasodilation of blood vessels, sometimes resulting in fainting or syncope. In many instances, this can be a relatively benign condition. However if syncope is a concern, a cardiac work-up may be recommended to rule out heart disorders.
It is encouraging that you have already had an MRI Brain, and EEG performed, which I’m assuming did not reveal any abnormalities. It also appears that you have had some cardiac workup with a heart monitor. If you are already seeing a neurologist, I would recommend continuing to follow up with them so that your symptoms can be monitored. If you have not seen one, I would seek one out for a formal evaluation. I am unsure what kind of EEG you had performed, but if the neurologist feels that there is high suspicion for seizure activity, they may recommend further monitoring in the hospital, where the EEG can be performed over an extended period of time.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.