Thank you for asking your query at DoctorSpring.
I understand that your son had a cut lacerated wound on the head which was patched up with glue to prevent scar formation. The fever could be due to an unrelated cause. The pain itself can cause rise in temperature. You can observe for 24 hours to see whether the fever is resolving. Meanwhile if you have OTC fever medication (0.4* ml or quarter tea-spoon of Tylenol oral suspension*.) you can give it to him 8th hourly in consult with your GP.
I recommend an ER visit under the following circumstances.
1. Fever not resolving in 24 hours
2. If there is pus draining or increased swelling at
the site, He might require an antiseptic
wash and prevent spread of infection along with antibiotics (ER visit asap)
3. Any additional symptoms like drowsiness, nausea or vomiting. (ER visit asap)
Hope this helps
Please feel free to ask followup questions.