Eating when nervous - I have to eat!

I'm a young musician and have a concert tonight, I'm very excited for it but also quite nervous and I've got that classic 'nervous tummy' thing with the classic 'nervous tummy' BMs if you catch my drift....

Along with this I also have zero appetite, despite being hungry. I know I NEED to eat, I'm playing the soprano saxophone which takes a lot of diaphragm work, and I have a tendency to get really spacey in performance and panic that I'm going to faint - eating properly definitely helps avoid this and helps me play better.

But, of course, the emet side of my brain says 'if you have no appetite that's probably a stomach virus' or 'you just had a soft bowel movement, probably shouldn't eat' etc etc, and then I get even more panicked because I've eaten and 'what if I v* in the middle of the performance' type thoughts start coming...

Any tips to get me calm? And what/when would you recommend eating?

You are proably hungry, just so hungry that you can't even recognize it.

I would just have toast and maybe some tea so you're hydrated, or some cereal. These are things I eat when I can't bring myself to eat but know that I need to. Or maybe a banana. all bland things

I agree with the bland foods - whenever I'm having an upset stomach/weird BM and know I should/need to eat that's what I do. Toast or crackers and bananas while sipping on water.