I've tried to look this up and the closest thing I've found is maladaptive daydreaming. Also it's important to stress, that when I write ''fantasizing'' I don't mean daydreaming about hot women or winning the lottery, I mean I seeing worst case scenarios for everything. I can go down these rabbitholes that lead to extreme discomfort, this could be pondering over whether or not I have some kind of illness, what implications that would have in my life etc. I think this is probably pretty standard stuff for people who struggle with anxiety, so I wanted to ask if you guys have any advice on what I should try to do. (I already practice mindfulness and meditation, though I am not very good at it). m