Hi,
Thanks for posting your query.
With the available described symptoms, there appears to possibility of allergic Rhinitis.
Persistent sneezing with associated headache suggests the diagnosis.
You should consult with internal medicine specialist/ ENT surgeon and should go for thorough check up.
You should go for chest x ray, erythrocyte sedimentation rate and complete blood count.
As such there appears to least correlation between present symptoms and past history of pneumonia.
You should take montelukast with levocetrizine, zileuton for relief of your symptoms.
Sneezing relief also cures headache.
You should also use Azelastine nasal spray.
Take steam inhalation for better relief.
Take care,
Dr. Mayank Bhargava

Hi welcome to Health care magic forum. Continuous intermitent sneezing means it must be due to allergyonly due to some allergens like food, or external like dress,powder, soap, flowers etc. which have allergens , they cause allergy to some people who are allergic to them.
Some foods, like fish, seafoods, brinjal, some fruits are allergic to some people. So when they consume them some people get allergy who are allergic to it,and get sneezing.
If the sneezing is not treaed promptly may get secondary infection by bacteria and lead to lung infection. Besides routine drugs there are new medicines to lower the frequency and intensity of sneezing , sometimes may stop the allergy completely, (montelecost+levocetrizine,)
I advise you to consult an E.N.T. surgeon to get rid of the sneezing and secondary infection. Besides i also advise you to avoid the things which are allergic to you , which can be identified by your own self by experience.
Wishing for a quick recovery and thanks for calling.