You should have to check your blood pressure and sugar levels either it may be increased blood pressure or decreased sugar levels causing that.
Also check your vision. Vision problems can also cause symptoms of headache
If you have any of the other symptoms of sinusitis
such as throat congestion
or burning of eyes and irritaion in the nose while taking breadth than think about sinusitis.
First have good clinical examination and then establish diagnosis and then take medicine or vice versa.
I hope I am sucessful in solving your query If you have more you can ask me.
Dr. Azhar Sattar