My 7 Year Old Son Had A Fever Of 103.9

My 7 year old son had a fever of 103.9 starting monday morning and he had loss of appetite, extremely tired, cough and sore throat. His fever went away by Tuesday morning but all the other symptoms stayed and he had also started having diarrhea. His fever then came back at a temp of 103.3 early afternoon Wednesday. He is still extremely tired and won't really eat anything. His fever then went away late wednesday night. It is now Thursday evening and It is back again at 102.3. He still has all of the other symptoms except diarrhea. What is wrong with my son?