pain killer

Hello fellow members!
I would like to know from those of you who are experienced enough to help me in this regard.
My period was due 10-15th of last month and till date I have no signs of it. I did an early pregnancy check last month but it was negative. However I have an appointment with the doctor next week to get a checkup until then I would like to know if I could take a pain killer or no as I have a severe migraine problem and I can't get better without the medicine. Is it okay to take a tablet of SYNFLEX(220mg) at this stage? Or should I wait?
Please help!