I have a friend who's entire high school experience was just like that. Hes a smart kid, but when he got to high school stuff got more difficult. Not just classes, but dealing with friends/relationships/extra curricular/college/etc. He started getting super anxious and hard on himself before major exams and stuff. His grades suffered a bit his sophomore and Jr year because of it and it had awful effects on his self worth. But his mom and dad and friends were all super supportive and never pressured him or anything.
I advised him to see our school counselor about it. I'm pretty sure most, if not all, high schools have a social worker who is bound by confidentiality (unless you feel you're a danger to yourself or others, then by law the social worker must tell someone to avoid a tragedy potentially happening).
Anyway, my friend saw our high school social worker for a while. Eventually my friend figured out he had major anxiety problems because he was afraid of failure. That's just his story, so I'm not saying you are the exact same. But I am saying that many times, high school and life just get to us. We start putting pressure on ourselves or we start believing we need to be the best. Id suggest going to see if your school has a social worker. Not only should that be helpful for your emotional needs, but they often can offer tips on managing stress, managing schoolwork, etc.
Never be afraid to ask for help from the people in your school! And don't be afraid to consider outside therapy as well. My dad always says that everyone should have a therapist, because everyone should have someone to just say whatever they want to.
And, with the Spanish thing, if it helps: I took french from 7th grade to 12th, and was in AP (Advanced placement) french in 12th grade. I graduated salutatorian from my school. I hope this is painting a good picture of me as a successful and capable person because... On my AP french exam, during a conversation, I literally said "je livre" which translates to "I book". I just totally got caught up in the moment, panicked a little, and attempted to salvage the situation lol. I still got a good grade! Not what I wanted, but good. We all make stupid mistakes, even on easy stuff, and that's super ok.
Good luck to you friend