Hey, doing better already here. (At least no longer sick) Although I still have frequent days where it seems like I cannot get anything done.
I think a big part of the problem for me is that I don't really allow myself enough rest. Even when sick, I tend to try and rest by playing games, watching movies or reading stuff online. But if I can manage to just stop myself and do nothing (really nothing) for 30 minutes, that seems to help so much more.
I hope you find a way to get up and running again so you can prepare for your concert and trip. But it's also fine if you don't, I think. You will get through it either way, good luck!