A word for a person who always needs there to be a problem?

I spoke to a woman who had several issues dealing with a common process we go through at work. I gave her several solutions to her issues and even explained that one of her main issues was not really even an issue, just something she wasn't understanding fully and actually had the power to manage and maintain. She fought me throughout our conversation and kept repeating that she was having these issues, even as I tried to reinforce that these were solvable and manageable problems. After it was completely clear that everything had been explained and taken care of, she was obviously hesitant to accept that things were actually okay and seemed to want to not be okay with everything, just sighing and repeating, "Well... okay. But.... okay."

It was like she just wanted to be mad, perhaps because she was just foul-tempered, but also like she did not want to let go of the problem. I talk to these people every now and then who just seem unable to let go of that pessimistic mindset and want there to be a problem. Is there a word for this kind of person or a suitable adjective? The words I've come up with that touch on what I'm thinking of are argumentative, irrational, disagreeable, and dramatic, but none of these fully encapsulate that certain quality of just seeming to NEED there to be a problem.

Drama queen is a colloquial (and perhaps a bit demeaning) term for "A person who habitually responds to situations in a melodramatic way."

Such a person is a worry-wart. The Free Dictionary's definition is:

Someone who worries all the time

Example, from TFD (same link as above)

A Harvard University study, hailed as the most thorough of its type to date, found strong links between anxiety and heart health: the sunniest, most optimistic individuals examined in this study were a whopping 50 percent less likely to have heart attacks or strokes than their worrywart counterparts.

My personal definition of a worry-wart is a person who gets worried even during the brief intervals when there is nothing obvious to get worried about -- what is he/she overlooking?