[17F] being bullied at school

I am a 12th student (pcm) who has GERD, anemia and sinus infection medical conditions. Due to these medical conditions I got bad breath. People around me react so harshly when I speak and breath. It's been 3 years since I have bb. I went to dentists, ent specialists they prescribed me lots of medicines which I am taking continuously although a slight change is seen but anxiety and stress make it worse.

So everybody at school knows that I have bb. Their reactions are spitting saliva, touching nose or holding their breath. But there are these COMMERCE students, during painting classes and practical exam they constantly made fun of me and even they did this in front of the art teacher also. But the teacher didn't say anything. Since I'm good at painting, those cmr students forced me to complete their practical and portfolio. While I was doing their work, they made lots of comments on my body and medical conditions. It could be just fun moments for them but I just cannot stop thinking about all these. I view it as bullying not physically but mentally. I did your work and you guys got 70/70 in practical and in return all you guys gave me is stress and anxiety for these 2 years.

What do I do? I have lost all hope and I think me being born was a sin. The school I currently I study in, it just feels like hell because of the students. See I am not knowingly doing this bad breath. I brush my teeth properly but my bad breath is caused due to GERD, anemia, stress, anxiety. For your comfort,I have stopped talking and in my defense, I don't speak a word when you guys harass me with your words. These 2 years were none less than hell for me. I am thankful to my doctor and parents who genuinely cared for me and listened to me.

Is it sin to have medical conditions that seem incurable?