I am taking nortriptaline 30mg for migraine 2 days now. having rapid heart beat after taking. shall i continue taking? quit it cold? taper off?

Sounds like: You are having adverse rxtn to the nortriptyline, and the dose you are taking is far too low to really prevent future migraine headaches. If you increase dose, you will have more problems. There are far better prophylactic options, and it is best to find a headache specialist, and consider other meds or even otc preps which are safer, more effective, and have less side effect potential.