I understand your concern.
Well symptoms of head injury can occur immediately or develop slowly over several hours to days so we usually advise to closely watch for 24 hours to see if there are other associated symptoms like vomiting,dizziness,disorientation,restlessness,blurred vision,irritability with severe headache.
As you have already taken Advil with little relief to your headache so you should take Tylenol and OTC Prilosec/Zantac/Metoclompramide and if you symptoms'll not improve in a hour then visit ER.
Avoid further use of Advil.
You can do cool compresses on knee and wear ace bandage.
Elevate you leg.
Do gentle massage with muscle relaxant ointment on back of neck.
If pain is getting worse then visit ER.
Use reply to let me know if you have further queries.
Please to not forget a positive rating.