Why is my singing voice doing this?

I have been singing for 5 years now and have been in choir since grade 4. My singing voice has been cracking up lately and has been very weak. My normal vocie is fine. I know it isnt strained because at school when I am at choir it works fine. :( I asked my music teacher and she said she doesnt know. It cant be because I am growing up because it works at school. I asked my friends they just think I strained it but I dont think I have. Otherwise it wouldnt work at school. I have no idea why. Singing is my life and I love to. Plz help!

What's different between school and the place where your voice is cracking? Maybe the type music you're singing is pushing your voice a lot harder than the music you sing in choir? Try singing your choir parts at the location where you're voice cracks. If it's OK there too, that's it. Otherwise it could be heat, humidity or maybe you're trying too hard when solo as opposed to singing in a group.

well music are differnt ,and it's your voice who say this music Belong to your voice,but your problem is normale maybe cause you eat something cause if you drink something cauld Will inflame your throat ,and don't sream or yell thoes thing will destroy your voice so stay away from them ,either not all music In line with your voice some of them aren't good for your voice .

well I just had voice lessons yesterday and she said to me my voice is cracking because I am just going through the process of getting a stronger voice