I often post a link to this blog and can only advise you to print it out, stick it in the medicine cabinet and glance at it occasionally. It gives advice on when to seek medical treatment when your DC have a fever.
please NO COLD BATHS. This is dangerous advice.
If in doubt call your GP.
How is your DS now, Scaley? My pediatrician advised that if temp goes over 40 degrees and / or does not respond to meds, to seek medical advice.