Hi.. The treatment for migraine is different from that of a nasal polyp which is slightly different from that of sinusitis headaches.. Usually migraines are diagnosed on clinical history where as sinusitis and polyps can be supported on investigations.. Hence if you are really confused on what is causing the headaches, I would suggest you to get the investigations done, which can confirm the diagnosis.. An X ray/ endoscopy/CT scan can help in diagnosing.. Discuss with your doctors regarding the same...