The stress is not all in your head so I would leave it at that. You know from your specialist that you definately have other problems and I'd just take what the GP says as confirmation that you have a problem not of your making and that it will take specialists and you to "fix." All I'd worry about was how to relax some and take some of the stress off. The finals are going to end soon if they haven't already, the car will get fixed so concentrate on doing some relaxing for yourself and anything your specialist has recommended? Any meds?

I'd "give up" the worry about the jerking. So you jerk, so what? It's just a physical thing your body is doing to help you cope. Concentrate on helping your body help you.

"We are all susceptible to fainting by activation of the vaso-vagal reflex that results in a lowered blood pressure, however, an individual’s susceptibility varies day to day based upon genetic make-up, dietary factors, psychological state, and triggers such as infection, dehydration, and alcohol intake."

http://www.hrtcare.com/neurosyn.asp