I have an eleven year old son, who for the last nine days has had very little energy - complains about being very tired, has a headache that we treat with ibuprofin/tylenol - no fever really, recently says stomach hurts, some loose stools, dizzy when he walks around, but every now and then he gets up to play, then I find him laying down again. I thought it was a virus and would run it s course, but when do I need to do more?