During my GCSEs, I was an incredibly unconfident student. This meant I never raised my hand. I never asked or answered a question, I never asked for help. There were many reason for this - I didn't want to make a fool out of myself or everyone to think I was an idiot, or just really stupid. If you're self-assured with an abundance of confidence, this may seem like a very foreign concept, but it's not a rarity -insecurity affects so many teenagers and can lead to so much extra pressure and stress during exams.
This negative mind-set affected me most in maths; not understanding one step could throw off the entire problem, and it meant I would get lost trying to figure out one tiny section, rather than asking and fixing it much faster. The fact I was surrounded by highly intelligent classmates made me much more concerned with how I would appear to them, and if I would be judged for not getting a seemingly obvious idea.
However, as exams got closer, the reality of how this issue would affect my grades became apparent. Raising my hand was still pretty terrifying, so instead I resorted to seeing teachers after lessons, or emailing them. Whilst this can also be daunting, it is their job to make sure you know the content and get the best grades you can, even if they seem harsh or uncaring. Your friends can also support you if you need help with smaller issues.
Ultimately though, the best thing to do not only for your grades, but your future confidence, is to work on being able to ask questions. The best way to tackle this is trying to change the way you perceive those around you. I typically saw my classmates as good-natured people, but as soon as it came to talking aloud, I convinced myself they were snide, and would mock me the second the opportunity arose. The fact is, people see you the way you see them. They will not care if you ask a question, and if they do, it's a bigger reflection on them than you - the opinion of one malicious person doesn't define you. You have to try and stay as logical as you can if you're starting to stress out - I know it's easier said than done, but it's possible. If someone else asks a question, your reaction is probably either agreeing, or not being bothered at all. It will be the same for others.
I know that the advice above seems easy in theory, but won't be when it comes down to putting it into practice. Just work your way up to it. Start with asking one question in the class which you feel most comfortable, potentially with the majority being your friends, and try to do that as much as possible. Raising your hand once can be a huge achievement, so be proud of your progress, and keep striving to improve!!
Remember, you're not strange, or stupid, for struggling with this - we all have our issues, and we all sometimes need a little help.