You’re not alone! This has been happening to me all the time lately. I keep trying to remember what it was like when I lived a normal life and wasn’t constantly worried about these feelings of questioning my existence and I can’t seem to remember... I’ve been doing a lot of searching lately and it seems that for me this is due to stress and just currently feeling unfulfilled, I don’t feel like I have a “purpose” right now which makes it easy to get down and start questioning everything - which by the way makes me feel even worse and ungrateful because compared to most people in the world, I know my life is great but for some reason I can’t maintain this feeling. I’ve been trying to make life moves to improve this and change things that aren’t making me content (switching careers, saying no more often, exercising, etc). At the end of the day, I don’t want to die. So my only other option is make the best out of this one life I have and carry on. I truly hope you feel better.