My 15 Year Old Son Started With Stomach Pains Saturday

My 15 year old son started with stomach pains saturday evening...we gave him gravol..by 11 he had started vomitting and then alternating between that and diarhea all night.. he developed a fever. The stomach pain is still there, not as bad and the fever is mild but still there. A clinic DR said he has a virus and it will pass but the diarhea wont stop and he is afraid to eat but the color of his stool is greenish