Don't 'sing through the soreness' or you'll risk damaging your voice. Do vocal warm-ups before you sing to make the vocal cords more supple and keep well away from tobacco smoke.
It may be worth experimenting to find your true voice - as Ron says, many people force what they think is their singing voice, when the real and more sonorous voice is quite different. If the choir has a voice coach, seek out a bit of one-on-one and explain your problem.