The dizziness on sitting is condition which can be due to many reasons. This is also called vertigo. It can be due to low blood pressure, otologic or problems in inner ear which is associated with nausea and vomiting or it can be disturbances in the balance centers of brain but it also cause speech problems and double visions. I advise you to visit a doctor and get differential diagnosis and proper treatment. For more detail;s, visit Dizziness.
I was getting very dizzy several times a day. I would be sitting at my desk at work and would be dizzy, only last for about 10-15 seconds. I went to the doctor and he said it was Veritigo and to take motion sickness meds.
I have suffered from anxiety and can see why you ask this question. When you are up and about keeping busy it can combat the anxiety and therefore combat the symptoms, but as soon as you sit down with nothing to do then the symptoms of stress and anxiety can re-surface. However, it might be worth having your thyroid levels checked out as this was the case with me. Every time I sat down I felt as if I was on a boat or off balance and then sometimes a bit nauseous. Infact, my symptoms have returned, which is what brings me to this website.