See if you can work on getting to a place where your happiness isn't contingent on your external success. Change thoughts like "I must get 4 As" to less rigid, dogmatic thinking, such as "I really desire to get 4 As, but I will survive as a human being if I don't". This fear / worry / stress has a positive intention - it is coming from a place of you wanting to do well and to be successful and of course that is a wonderful ambition to have. The problem here is being completely dissatisfied with failure.
I want to share some perspectives here. If you want to be as successful, fulfilled and happy as you can be in life, it will be hugely beneficial for you to become comfortable with failure. Failure is pretty much necessary for eventual success.
Write down a list of ways in which failure could be a good thing. I'll give you a few examples.
- When you fail, you can learn a lot and you now have feedback you can work with to improve.
- Failure helps you to discover the boundaries of your current abilities - and thus helps you to understand "where you're at" and how far you have to where you want to be.
- Failure is a great reminder to stay grounded and not to become too arrogant.
Beyond that, I would then rethink the way you view this. You are currently seeing it in a binary way - 4 As = jackpot, win, brilliant, gold. Anything less = TOTALLY UNACCEPTABLE. But this way of seeing things is too dogmatic, too binary, too simplistic and reductive to be of real value to you. It won't really serve you to see things like this. A much better cognition / belief would be, "I would really love to get 4 As. I will naturally be disappointed if I don't. However, it won't be the end of the world by any means. I will still be surviving as a human being. I will still be breathing, I will be a fully functioning human being and I will still be whole, complete and worthwhile. I have put a lot of work in for these exams and even though I haven't quite done as well as I'd hoped, I've still got some really good grades here".
You are whole as a human being. You are complete. You are fully functioning. You are worthwhile. You don't need external conditions or success in order to feel happy. You can do that right now. Count your blessings. Make a list of ten things you're grateful for right now. Realize that exams aren't everything in life - they're just letters. They have some meaning, but only the meaning you give to them. Don't be 'owned' by a few letters. It's not worth it.
Best of luck with this