Oh, that's not a good scenario. First, you should determine that it is indeed ich, and not something less contagious.
Ich causes salt-sized white spots on the fish, and the fish will act essentially normal and continue to eat until it has been sick for quite some time (a week or more). Velvet causes a fish to sopt eating and breath rapidly, followed by death in a few days. Brooklynella is common in newly acquired clownfish - the fish will develop a white slime, will swim weakly, and will stop eating.
If you post a video and pictures, we can help you diagnose the issue.
What other fish are in the tank with it?
Treatment is going to be difficult to impossible while you are gone, is there somebody at home who could dispense the treatment for you?
Jay