Thank you for posting your query.
I have noted your husband's symptoms. The most likely diagnosis in his case could be a migraine with visual aura. The migraine attack can get precipitated by delaying meals, hypoglycaemia and workout at gym. The headache in migraine can last upto 72 hours.
However, as this is the first severe headache and there was blurring of vision too, it may be better to investigate to exclude any other causes such as brain ischemia (lack of blood flow to the brain). This would require investigations such as MRI brain with angiogram and carotid doppler.
I hope it helps. Please get back if you have any follow up queries.
Dr. Sudhir Kumar MD (Medicine), DM (Neurology)
Senior Consultant Neurologist,