Performance on Wednesday-Help Me!

Ok, I've had the flu for the past week, which caused a lot of problems, but whatever. Last week, however, I performed a song called "I Never Saw Another Butterfly" at a Jewish arts event with my school choir. Apparently, I was amazing, and my music teacher invited me to sing the song again, this time at a chamber choir performance this Wednesday. I have a cough and I'm still a little congested. What should I do in the three days I have to prepare me to sing this song. It goes towards the top of my range (G5) and it's a 4 minute, very emotional song. I know to drink a lot of tea with lemon and honey, but what else?

Ok, I've been staying hydrated and everything and I CAN'T SING! I sound terrible. I should be better by Wednesday, but I'm really worried!

No luck. Choir rehearsal tomorrow morning. I have a solo. I'll need to sing. Maybe my teacher won't make me. I'll have to ask not to sing my solo.