In the past i've had chicken pox & mono which both have the epstein barr virus what are the chances of having chronic fatigue syndrome?

Same as anyone: Almost everyone has ebv infection at some point in their lives. And chicken pox is caused by varicella virus, not ebv. So just because you have had both of these infections does not make you any more likely than anyone else in the general population to develop cfs. More likely you would have other predispositions to the illness. But the answer to your question is your risk is same as all people.

Possible: Chronic fatigue syndrome is strictly defined by specific symptom criteria. Many disorders with chronic fatigue as a primary symptom of illness are seen associated with a number of viral infections including Epstein Barr virus (the cause of mononucleosis). Many other environmental toxins including mold toxins and chemical toxins can cause chronic fatigue. A very stressful life event may cause it.