I'd really appreciate some advice. My DS is 13 and recently moved to his secondary school. He is doing well academically and is bright - but he worries so much. He got himself in a stew about his common entrance last year (until his first exam when he realised it was easy). He's now worrying about GCSEs despite the fact that they are 2 years away.
He worries about getting good grades, to then get a good job - at 13!
We have a happy, stable home life. Our younger DD is the opposite - uber confident.
My DS(14) is a bit of a worrier as well. On the positive side it does mean he prepares for exam and does well but that tends to breed high expectations for himself and from teachers. I try to lessen the worry by talking about "all you can do is try your best" and making sure I don't inadvertently put any pressure on him (the exact opposite of what we did with DD1!)
I would take his worries seriously and talk about what exactly is bothering him but then move him on to thinking about now rather than things that might not happen.