my 4 year old grandson has been running a temp ranging from 103 degrees to 100 degrees for 2 days. The thing he complains about the most is when he looks up or coughs the back of his neck hurts...The Dr. said he had a sinus infection. Can that cause his neck to hurt like that? Felt for swollen glands but they seem ok. We just want to do the right thing. Do you have any input?