hello and welcome to HCM,
Since you have been slapped and following that you seem to have a shock
kind of state which may manifest as giddiness and headache
It is very common in slaps and people do not realize that a slap can be that harmful.
Having said all this let me assure you that in almost 90 percent of the cases if properly treated you would not have any problem
Make sure you have an ENT consult and get a full examination of the drum and also perform an audiometry
examination so that we can have a good measure in follow up.
Keep your ears completely dry and do not put drops, buds or water inside the ear
Avoid head bath for the next one week
Take a course of antibiotics and antihistamine in consultation with your doctor
Go for regular follow up
get a neurological consult also if the headache persists and also impress upon him to take a CT brain to be on the safer side
take care and get well soon
Dr Sriram Nathan