Welcome to HCM ..
I read your query and it seems that Headache and dizziness
with nausea sensation makes me to think of possibility of Benign Paroxysmal Positional Vertigo ( BPPV )
also a simple migraine
can cause similar symptoms .
I wound suggest you to get prescribed for
1) Tablet Betahistine
8mg to reduce symptoms of dizziness .
2) Tablet Acetaminophen
650 mg to treat severe headache
You should also know to prevent BPPV with some information :
Be aware of the possibility of losing your balance, which can lead to falling and serious injury.
Sit down immediately when you feel dizzy.
Use good lighting if you get up at night.
Walk with a cane for stability if you're at risk of falling.
Work closely with your doctor to manage your symptoms effectively.
BPPV may recur even after successful therapy.
Hope I provided useful information .
Thanks & Take Care .