I have been having dizziness, lightheadedness and brain fog for the past year, additional symptoms are heat intolerance, at times decreased appetite, fatique, muscle aches, light sensitivity, vision problems, exercise intolerance, shortness of breath, heaviness in chest, tremors, and occassional near syncope episodes where I get extremely hot, sweating from head to toe, extremely dizzy, nausea, palpitations and my arms and legs go limp. This will last for a few minutes and decreases. Afterwards I feel still dizzy but not as bad, hot and wiped out and will sleep for a few hours afterwards. The doctor said it was not my heart even though my heart rate ranged from 50-150's on 24 hour holter's monitor. thyroid, ana, anti dna, sed rate, cortisol levels normal, all lab work normal except epstein barr showed old contact, neg for early antibodies. The dizziness and brain fog is the hardest for me, especially when i am driving to work and have to pull over because I feel like I am going to pass out. I am starting to feel like I am a mental case. The heat seems to triger the dizziness and increased heart rate. My head constantly does not feel right. Recent ekg shows rsr with bbb in v3, did not show up in ekg months ago. Supine sbp in 80-90's, upright sbp 100-110's. Any advice, suggestions or possible causes would be so greatly appreciated!