Sons anxiety

Hi

I'm just looking for some advice, I have a 15 year old son who’s anxiety issues seem to be spiralling out of control. Had issues with school over the last couple of years, not going to school leaving school, seemed to get it under control then obviously covid and lockdown. He then went back to school seemed better and happier then school holidays went off the rails a bit but under control again. Starts back school today found him missing in the middle of the night got him home anxious shaking like a leaf. He worried he fails all his exams and today will be his first day of 4th year, I put no pressure on him told him all I ask is he goes to school and tries and if he fails everything then that’s ok cause not everybody likes school and we will find another way.

sorry for rambling on but any advice would be great cause I feel as if I’m failing him.