Are you on any medications?
Are you diabetic or hypertensive?
Any investigations done?
What are the specialists you have consulted?
Effexor XR takes almost three months sometimes to show its optimal effects. So waiting for that duration is advised, since your investigations are normal and as you mentioned it may raise bills, if we consider all the investigations and imaging studies. Still a MRI of brain is advised and serum electrolytes needs to be done if they have not already been done to see serum calcium, potassium and magnesium levels, abnormal levels of which can cause some of your symptoms. Organic causes should be excluded before other functional diagnosis are considered.
Since all your episodes were aggravated during particular activity or had precipitating reasons, one should not worry much, as they can further potentiate or increase the symptom complex. You can choose either of the following. Wait for two more months to see benefits of Effexor or get the investigations done immediately.
Hope this helps you. Your follow up questions are welcome.