I can relate. I don't know that my attacks or anxiety feel the same as yours, but I have been in that same situation. My last year of college was filled with lots of work, stress, and pressure. I really pushed myself. Of course, in addition to my degree...I was diagnosed with Crohn's disease. Takes the fun out of finishing up. But it taught me a lesson. You can push yourself to far. And sometimes putting on a brave face and digging in won't always make things better. We aren't machines. We are humans. And unless your a soldier in battle, the only life you risk is your own.
It's easy for people to say not to worry or that you are being silly. They don't understand. Ignore them. Listen to your gut.
My opinion (and only that) may be trying one of these ideas I have used to get past trigger areas:
1) See if you can break down these assignments (or worries) into smaller chunks. Set small goals that are attainable. Don't look at it as a overwhelming challenge, but a series of smaller ones.
2) In regards to classroom issues, imagine you are an actor in a movie. Play the role of a confident and courageous hero. This sounds silly but it worked for my wife you had terrible social anxiety. And remind yourself that everything that happens was part of the plot. Do not let any of it get to you. When you leave class, try to leave those events there.
3) You sound like an intelligent and determined person or you would have made it this far in your education. Give yourself more credit. But remember, it's okay if you do not ace something. Sometimes we put some much pressure on ourselves that we cannot possibly reach our expectations. You are so close to the finish line. You can make it. W are all rooting for you. Do what you need to do to get there. You do not need to win (metaphorically), just finish.
Hope that helps.