Apple ID verification problem
My phone just out of nowhere started asking for apple id verification and the notification keeps popping on the screen every second or two after I close it, and even when I type my password it keeps doing the same, I've tried many things, including signing out off my account but it keeps loading for a short time after I press accept on the icloud message and it goes back to the settings screen, also changed the password but nothing happened and I've already updated the phone and everything; it's very annoying because it doesn't let me open barely any apps.
So if anyone could help with this I would appreciate a lot.
iPhone 6, iOS 12