Suggest Treatment For Shoulder Pain And Fever

My son, age 7, got up at 2 am this morning crying with shoulder pain. I questioned him to see if maybe he had fell at school or bumped it in any way during the day. He said no and said it had hurt all day at school. This is a child that does not complain about being sick or hurting. His body felt really warm but his face was cool. I gave him some advil for pain and laid down with him until he fell back asleep. I then woke him up for school at 6:30 and he didn t mention his shoulder until we were on our way to school and he said his shoulder really hurt. The school nurse called me at 11 and said Cooper had a fever of 102.2. When I picked him up his color was off, he said his side and tummy hurt and his head hurt. The nurse said there was a fever virus going around and that was probably it. He has not had fever since about 1 but I have a concern about his shoulder hurting all of a sudden. Thank you for your time. Paula