Suggest Treatment For Child Suffering From Diarrhea And Stomach Pain

My son is 7 and has been having problems with diarehia for about a month and a 1/2. He doesn t participate at resses, doesn t want to do anything but lay down. He really complains of his stomach hurting and feels like throwing up as well. The docter I asked a few weeks ago said try yogurt- but that has done nothing. School is difficult for him and he is really uncomfortable- what should I do??