I read your questions carefully and I understand your concern. Migraine headache is a clinical diagnosis, that means there are no specific tests to prove it, it is a diagnosis which is made by history, there are certain criteria which if fulfilled make the diagnosis and do not necessitate any further testing. When in doubt imaging tests can be done to exclude other causes such as brain tumor for example, but only to exclude other causes, not for migraine, no test diagnoses migraine. Regarding the treatment if you only need to take it twice a month and it is effective I don t really see the need to switch it, it s one of the more harmless alternatives. If it is not effective (remember you have to take it as soon as pain starts), you could try drugs belonging to triptans class such as zolmitriptan, sumatriptan etc, but only if nimesulide/paracetamol is not effective, if it stops your pain I wouldn t change it. I hope to have been of help.