What exactly are your fears based upon? Depending on the fear, one of the only advices I can give you is to monitor your symptoms. While this may not help some, keeping a solid record of your symptoms, even if it's something as simple as a journal, can remove some of that unpredictability (and make it easier to describe to a physician). As for fears that certain symptoms/illnesses will come or resurface, try looking up preventive measures in order to combat not only the symptom/s, but your fears that it could come back.

(Sorry if this isn't much use, but I hope it does help.)