I had some sort of anxiety when I sat my igcses too. didn't really know anyone in the exam hall and I felt like everyone would stare at me. But, after going in the first time, it wasn't actually that bad. Nobody truly cares to stare at others. Everyone is concerned with doing the exam. I became less anxious everytime I sat an exam.
Now that I do A levels, and look back on my social exam anxiety or whatever it was. I realise those were sweet days. Nothing beats this current stress.