I am really sick! Please help!!!?

I have a some sort of flu that is affecting me really badly. I have had it for 4 days now and I have eaten practically nothing apart from gs, half a tinned pear, 7-up and water. I have vomited over four times now and it is really bugging me. I have my friends birthday party tomorrow and I am still wondering if I should go if I am feeling any better. My mum says it might be gastric flu but I am not sure. Please help and fast! Thank you so much for all your answers, I really appreciate them.