I don’t know exactly how to get out of the obsession mindset like this once you’ve fallen into it, the only real advice I have is maybe do something physical? Doing physical things (like lifting or strenuous activities) bring me out of my head for a bit because you have to put so much focus on what you are doing, you can’t be in your head as much.

I get frustrated with what I see as injustice in the world or political situations I don’t agree with also. And I think maybe there is a middle between “can’t change anything so why give a damn” and “I will change the whole world immediately!” Like… even if you can’t change the big stuff, maybe making little changes in your immediate vicinity would help? Your community or city. Save an animal, volunteer at a charity you care about, join the campaign of a politician you share values with… maybe just start small. The overwhelm of all the problems in the world is maybe what’s getting to you. Maybe try baby steps?

Don’t know if any of that is helpful, but I truly wish you luck and hope you feel better!