Help with academic burn out

Good Afternoon , I've been struggling with a lack of motivation for almost 2 years. It all began near the start of my GCSE exams when I was under a lot of stress. I began to feel disconnected and like I was watching myself through someone else's eyes and I began not caring about studying and the future. This feeling has persisted and I am now in my second year of Sixth Form and I am struggling to find my determination to keep going forward . I study for a long amount of time yet my test results are always bad and my grades suffer. I feel helpless and lost and I really want this to just stop because it's been interfeering with my home life a lot and also jeopardising my future since I phyiscally cannot will myself to study because I feel unmotivated. Is anyone else feeling the same or in a similar way? what would you suggest I start to do so I can finally break this cycle ? Thank you for reading.