Greetings.
Just relax and don't panic. Better take your son to any nearby doctor, who determine the reason behind the
fever by examination and necessary blood tests etc.,
Sincere advise for betterment of your son(or in general anybody) is that do not give any medicine prior to doctor visit(
self medication), as it alter/ delay/ become over or low dosage/ all of which affect not only outcome of treatment but also dangerous effect to various organs inside the body if not taken without proper prescription by doctor.
In this situation tablet
MOTRIN shouldn't be taken(given) more viz., 2 or 3 or more, as you wish , since you don't know at
1. what dosage you are giving it to your son?
2. How much/how long it should be given? Can it be given to your children? Is it necessary for your son? etc.,
all are decided only by your doctor after personally seeing him.
Meanwhile at home give him cold(not ice cold) compress all over body with help of 5-6 towels for 10-15 minutes. If towels become hot take out , dip it again in cold water and repeat again within that 15 minutes. Wait for 2hrs and repeat again for 15 minutes till you go to a doctor.
Note:
These are just guidance and not a definitive treatment as I haven't seen your son personally.
Hope you understood the seriousness of self medication and it helped.