Oh, your poor thing
Ok, so try very small sips of water...and flat lemonade. Try lying your baby down next to you, skin to skin, and just letting her nurse as and when she wants. But get someone to bring her to you.
Fenugreek is a great natural milk booster, you can get caps from Holland & Barrett, and they work in about 24 hrs. I tried them, before I had reflux diagnosis, and my boobs nearly exploded!
Get well, and as soon as you feel you can drink something, drink! Ditto eat...but go for bland, plain boiled rice, plain toast etc. Try the little sips. Most bugs are past their worst within two days, any longer, give your doctor a call and see if there is anything you can take for dehydration that's compatible with BFing.