I need advice

I get so much anxiety when doing math homework, I always think I’m going to fail and it keeps me from succeeding. I’ve never in my life had problems with math, I’ve always been the best math student (only there cause in the other subjects I’ve been average), and since I started college I got my first C’s and B- and it’s so frustrating and I can’t concentrate, I can’t even do a simple exercise without rethinking my whole existence. What should I do? I’m going crazy and I feel hopeless