I would put your immediate well-being first. If a piece of toast is going to make you feel better, eat it! You can get right back on after you feel better. Otherwise, I would suggest some chicken broth... Feel better!!
You will be eating so little in the next few days it shouldn't matter if you go off plan. Just restart when you feel better. Keep drinking lots of water and try chicken or tomato soup to settle your stomach. Hope u feel better soon.
The exact same thing happened to me except I was in Day 11. I had to go off the plan for a while and I am just now back on. I know what you mean the last thing you want is meat after throwing up, all you want is toast or crackers. I empathize. Don't worry you can restart once you feel well again. I did.
I ended up living on peanuts and Cheerios for a couple of days -- I figured I wasn't being THAT bad since Cheerios are Phase 2 and, well, I liked the peanuts so that's probably more rationalization than anything
I seem to have slept off the rest of the flu, and I'm back on track for day 5 and feeling good! Hooray!