Please please help me, I'm fretting over this)':?

Can high school second semester grades be changed? I had just gotten my report card at the beginning this week and noticed I had a B in drama. I am a pretty good student and probably one of the top 2 in my drama class. The teacher even wanted me to be in advanced drama for the school plays. I remember asking her if i could redo my final monologue because, being a perfectionist, I didn't do too great. She said I could but the final week of school when I brought it up again, she told me not to worry and that I got a 100%. I also checked all my grades online a few days after school got out and it said I had a 97% in drama. This teacher has started to be mean to me after I said no to advanced drama and even marked me truant just because I didn't say "here" loud enough. Is lying to me about getting an A tolerated in schools? Can I get the principal to change my grade to an A? I'm very motivated and seeing even that unjustified B crushed me. Any suggestions on how to change this? All answers are appreciated(: