Hi,
If both the sneezing and headache began since past few days, it could be attributable to sinusistis. Any fever, cough, runny nose?
If only the headache kicked in recently:
1. Benign exertional headache. This is related to activitiess like bending, coughing, sneezing. Nothing to worry about.
2. Something worrying within the area of head and neck. Look out for any other worrying symptom that started since not long ago. For instance any limb weakness, altered behaviour etc.
I would suggest that if u have not suffered from this symptom before, u must go and see a physician.
Good luck