My grade in my math cl sucks?

I don't get extra credit in the cl, we only have four quizzes and three exams. I've done poorly on the first due to missing the first two cles and not getting crucial info about one part of the test that I THOUGHT was right (but I WAS wondering why I had to do so much work on that part). I took the second exam recently and I can tell you right now, I failed- I completely blanked out when I got the test, I was stressed because I knew this exam would determine whether or not the highest grade I could get in that cl was a B. Now I think the highest grade I'll be able to get is a BC, and I usually get lower than the highest grade expected, so I'm really scared- I don't want a C or worse on my second semester report card as a freshman. I tried talking to my professor before by asking him to allow me another chance to take the first quiz I missed (appointment I couldn't miss, so I guess it was an emergency) since everyone got a second chance towards that quiz and I oly had one (I got a B on that quiz but an A on it would've helped me out a lot) as well as an extra day to study before I took an exam based on a quiz that I had no idea what was going on in, but the professor said no, and to just try my best. That didn't turn out well, but the second quiz I got I aced it and got excited, thinking I would ace the exam, too. I didn't. Would there be any way I would be able to convince my professor to give me extra credit or a second chance at the test or something? What would be the appropriate response? I got a B in his pre-calculus cl, and I don't want to end up dropping his cl because I missed a few classes in the beginning and I wasn't able to get back on my feet again. Its midterm, and I think I have a CD (above 65%) in the class if I were to include the exam I took, and exactly a C (70%) without the exam. I have one more quiz, exam, and then a final exam, which is 66% more than a usual exam.