Hello there could be many causes for this which includes migraine, sinusitis etc.kindly consult local doctor

U may have migraine. Consult a neurologist for treatment.

Acute attack of Narrow Angle Glaucoma on that side of eye can also give you severe unilateral headache with red eye. Kindly see your ophthalmologist too apart from neurologist to rule out Migraine.

Hello there... I understand your concern about your health condition and I appreciate that...there are many reasons for headache it may be due to increased blood pressures, migraine, cluster headache, refractive errors, meningitis,sinusitis,increased intracranial pressure, reffered pain from somewhere else... So detailed history and examination with relevant investigations is necessary... Kindly consult nearest neuro physician they will do the needful.

Kindly consult a neurologist to rule out migraine or cluster headache or any other causes.