Help!! Haven't eaten!

I haven't eaten in a day and a half due too feeling sick and vomiting. I'm dehydrated and every time I drink water I vomit it up. I've been to the medical centre and had an injection to stop the nausea. I don't know whether I should try eating or not. Do I need to go to hospital if I can keep and water or food down? I heard if this happens you have to get a drip cause you can't drink or eat anything. I know this is nothing period related but was wondering if anyone had any advice!! I feel like crap