I think those fears of the future can arise any time there are major life changes going on. I'm currently unemployed and I have to go a couple of rounds daily with fears of an uncertain future. Changes in major relationships bring on the same sort of thing.
One thing I've found that helps is to create scenarios for both good and ill. Think of the good ways that the future can play out and feel how good that would be. Then think of how bad things could play out--and then how you would get past the bad stuff and how good that would feel.
In other words, figure out how to arrive at a good place, regardless of what happens.
[I'm really stressed about the job search, so I think I need to do more of this.]