Brad seems to be in a continuous state of anxiety though he is unable to identify the source of his feelings. the most likely diagnosis for brad is:

The answer is generalized anxiety. The symptoms of this disorder is that the person tend to always expect that there is a disaster that will going to happen and also they can’t stop worrying about health, money, work, family and everything under the sun. Generalized anxiety disorder is defined by exaggerated anxiety, excessive worrying about everyday life events with no basis and obvious reasons.