Why am I having a hard time in Algebra 2?

@DogsAndMath23‌ the quizzes are similar to the tests, but are on fewer sections, so it is ultimately easier to study for. Unfortunately, my teacher gives tests that take an enormous amount of time to finish, and there is no time for checking for computation errors! I understand the material, but I get test anxiety and I blank out. On the very first test of the year, I got a 96, somehow, someway, and now everything has been going downhill. On the last test, which I got a 72, I was sure I mastered the material. What do I do about my test anxiety? Should I just drop the class, since I’m struggling so much?