Hello dear, I can understand your concern.Though you have many co-morbid factors like Obesity,anemia and Diabetes,but severe unilateral headache as in your case,is unlikely to be due to any of these factors.Most common cause of severe unilateral headache is Migraine.Migraine headache is episodic(lasting from hours to 1-2 days),unilateral,throbbing (pulse-like),associated with nausea,photophobia(increases on exposure to light),phonophobia(increases on exposure to sound) and visual aura(like seeing flashing zig-zag lights).Other causes of hemicranial headache can be primary headache like-Paroxysmal hemicrania,cluster headache.But,these primary headache comes in short duration episodes(seconds or minutes,which is probably not the case with you).Secondary cause like a space occupying lesion in brain can also cause persistent hemicranial headache.Please visit a physician,so that he can examine you well and consider to get a brain imaging(like computerised tomographic or CT scan) if he feels so,to establish your diagnosis.I hope it helps.