What Is The Treatment Of Dizziness And Less Appetite In Children ?

My Grandson is 23 months old and every month he gets ill with high fevers, lethargic, weak, sleepy,crying on & off when awake, nausea, some vomiting, and no appetite. He drinks juice and sometimes milk. My daughter has taken to the hospital and Dr s office every time, but they give her antibiotics or tell her to give him Motrin or Tylenol and that he should be fine. Yet it happens again and again. Poor kid has had so much medication I am concerned he is loosing weight and looks so pale and out of it so much. Is there anything specific we should be looking for to help these Dr s figure out what could this be. Please help she is on her way to the hospital now.