I would give plenty of fluids, maybe give an ice pack wrapped in a towel to put on his neck. Give him some ice chips to suck on if he doesnt want to drink anything.
Some moms here would suggest SA to bowel tolerance, but that will be hard if he is not eating anything or wanting to drink much.
If I did medicate it would be advil, however I wouldnt unless he was really uncomfortable or had a hard time sleeping. The fever alone would not be a reason to medicate IMO.
My DD will drink warm soup broth during times she wont eat food. Maybe give him something like that.
Avoid acidic drinks as it stimulates the salivary glands which can be painful.