Hi Eugene,
The rapidity which these doctors pronounce anxiety and depression as the cause to everything that they cannot explain, verges on 'evil'! Are you normally an anxious person?
What tests have they done so far? Have they done a two or three hour GTT (Glucose Tolerance Test)? Have you had an extensive work-up of tests?
This is a good article for the types of things that need to be investigated.
http://www.aafp.org/afp/980215ap/poncelet.html
As your symptoms started to happen just a few days after the colonoscopy, I would wonder what drugs you may have had for the sedation or anaesthesia for that procedure. You sound like you may be quite sensitive to medications therefore a
toxic cause of the symptoms you are having could be reasonable to exclude.
I'm sure others will give you lots of good ideas.