I don't know whats wrong?

I have had these headaches for about 2months in the back of my head kind of like this pressure on both sides of top of my neck/head. Not sure if its stress or something. I have had encephalitis when I was 13 and im 22 now dont know if that has anything to do with it. Iv been suffering from derealization about 2months ago. I over think everything it seams like now like am I really here but its only about once a week .Please is this ever gona go away bc it pisses me off bc i cant be happy anymore. Tell me what you think.