Thanks for the query,
I understand your concern
Your headache can be due to many causes like migraine
, problem in the left side of the brain, tension headache
and so on. A physical examination is needed to clarify the diagnosis. In view of the recent left sided pain you need a neurological evaluation including a CT scan to rule out secondary causes of headache. Your treatment will depend upon the cause. If the scan is normal you may benefit with anti-migraine treatment which includes medications like amitriptiline, propranolol
etc along with regular diet and life style changes. You need to avoid coffee and try to find out the precipitating factor which will reduce the severity of headache.
Hope this helps