Feeling fatigue since a week after tetanus shot. Can tetanus shot cause chronic fatigue syndrome?

Not usually. I have never heard of a tetanus shot causing chronic fatigue syndrome. It is much more likely to be related to your sleeping and eating patterns, if/what drugs you are taking, stress levels, etc. Medical causes might include thyroid imbalances, parathyroid problems, even depression. If the fatigue persists, see a primary care doctor. Good luck!