Welcome Back, I'm happy you have been doing well overall but sorry to hear the anxiety has returned full force.
I know for myself exams are a sure thing for anxiety so you are not alone. Many people have anxiety before exams. You said you are using your coping tools and they aren't working, keep using them anyway, especially breathing.
I agree with Hibee about
Mindfulness, I find it is most useful tool I have in my tool bag. I'm going to post one of my favorites off of youtube, try it and see if it helps any.
/www.youtube.com/watch?v=HT_ZvD94_kE&list=WL