Thank you for your response. It has been a couple months, and I have finally discovered the source of my condition. I am sensitive to the "flicker" of certain lights, including fluorescent lights and television screens, which is caused by the vertical refresh rate being at a particular frequency that triggers the symptoms. Apparently this is likely caused by prior neurological damage, and results in all of the issues I have mentioned in my above post. There is barely any information on the web about this condition, but this article by Dr. Richard Conrad has helped immensely:
http://www.conradbiologic.com/articles/SubliminalFlickerI.html
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 can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
Anxiety is a psychological and physiological condition with a multitude of symptoms. For some people, they include heart palpitations, muscle tension, fatigue, nausea, chest pain, shortness of breath, headaches, and GI symptoms such as diarrhea to name a few. Anxiety can also be accompanied with panic attacks such as a feeling of impending doom or death. You may have developed a phobia.
I would suggest you follow up with a physician (primary care) for a general medical examination. He/she may then refer you to a specialist (such as an ophthalmologist, psychiatrist, etc). Further workup (such as an MRI of the brain, etc) would be decided after a thorough examination.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.