The increased heartbeat is just one of the early signs of severe dehydration, so you need to get fluids in you some way, crushed ice works well in these situations, spoon it up and let it melt slowly in your mouth. If even that doesn't work, get to the E.R. and get an I.V. started. I nearly died with the flu one time by allowing the dehydration to nearly kill me, the doctors said if I had waited 4 more hours I'd have been gone. Please don't wait if all else fails.
You can go a while without eating, but you need fluids. If you can't keep fluids down, you need to go to the hospital, they'll give you fluids through an IV. You're heart rate sounds fine, but I don't know what your normal heart rate is. If it's been more than a day that you haven't been drinking anything, or you vomit when you try drinking anything, get yourself to the hospital before you dehydrate.
If you're having trouble keeping even water down, try sucking an ice pop. This was advice given by my pediatrician when my son had the flu and threw up EVERYTHING. But the ice pop worked. As soon as I could I got Gatorade into him because it has electrolytes which is very important if you're going at it from both ends. If you have a caregiver, maybe they can make ice pops out of Gatorade. That would be the best thing for you. I hope you feel better soon.,