Taking 1mg klonopin, (clonazepam). 5am &. 5pm. Getting trembling shaking feeling internally. Is this a side effect of withdrawl or breakthrough anxiety?

Could be either. Could be either - are these the symptoms that led to your taking Klonopin (clonazepam)? If so, may be breakthrough anxiety since for most people Klonopin (clonazepam) would have a longer duration of action.
Depends. If you get the Anxiety between 9-12 hours after the first dose that would be more likely. Typically break through is not seen as much in my experience when the twice daily doses are 8-10 hours apart of klonopin (clonazepam). Please discuss with your doctor/psychiatrist to discuss and gather more details before reaching a conclusion for a plan . Take care.