Thanks for the query to H.C.M. Forum.
Since, headache you are having from last 1 & 1/2 years and pain is on right side of head & sometimes left side .
Means pain is not related to a particular site , so no chance of any localized disease ( pathology).
As all tests are normal , so we have to consider it as a psychological pain , may be due to tension ( work related). Anxiety
, Chronic sinusitis
( if you have continue coryza
( common cold
) may be one of the foremost reason this type of pain.
In my opinion consult a psychiatrist
and get his opinion.