I am 16, female, no medical history, and on no medication or treatment.Please help! Today i started vomiting after feeling sick since sunday, at first it was purple with food in it, about an hour later it was clear but coloured purple with yellow foam in it, an hour later it was the same and the same an hour after that, but there now it was a black grey colour with yellow foam in it, it wasnt cloudy but more clear, after the first time i threw up it didnt taste like vomit but weird like somthing i hadnt tasted before ? I also have the runs and a very very sore back and head, please advise me! Oh and i am really thirsty but if i drink water i just throw it back up? I throw up almost every hour.