My voice sounds scratchy when I sing?

I started camp a few days ago, and my teacher has me singing very high up during this class (Boadway pop choir) but the highness doesn't seem to be an issue though. But everytime I have sung this week so for about three days, everytime i sing, more so when i sing high, my voice gets scratchy and feels flemmy and week. No matter how much water I drink it doesn't seem to help. It's only when I sing and last week my voice didn't feel right and was sore off and on? I was having nodule like feelings but I don't think I sing enough for that?Should I see a doctor,because I have my cam[ and I'm going to be singing everyday, and I have to sing out of my confort zone (my highest note so far, a high F#)and I just don't want to hurt my voice, especially if it's already hurt. Please help.