Havent been able to keep anything down...PLEASE HELP

This isnt new to me, and I've called my doctor and am waiting on a call back, BUT I haven't been able to keep anything down (not even water) since 9pm last night...it is 3:15pm where I am now. When should I go in for fluids? I'm 18 weeks pregnant. Just need some reassurance that I won't be going in for nothing because it's such a long wait at the ER and I have two kids I'll need to get a sitter for. Help me out ladies!