Feeling sick might be to do with your inner ear feeling the two different earthquake waves but them not being strong enough for you to feel them conciously - sorta like carsickness without the insurance cost...
The plates will be active at the moment because of the two major events & related tsunami's earthquakes - the tectonic plates are a mechanical system and as such they are all interconnected... (im reminded of a star wars quote here...) which means a large event on one plate boundary will impact and have effect on others..
I did geology @ both college and university levels - in which, between looking at rocks, beating the crap out of rocks, drawing rocks, and avoiding starvation crazed welsh sheep - I learned about the joys or otherwise of earthquakes with emphasis on when its time to run...
for example - when the sea starts going out for miles for no noticable reason - and you havent been on the crystal meth - its generally not a good idea to follow it to see where its gone - because it will be back momentarily - and being in/on the next county/country/continent would be advisable.
(the above is almost verbatim from my old college tutor - who managed to cut out half a window demonstrating how quartz is harder than glass - and confused a female student for his wife.... dont ask - soon after he retired on health grounds... for which the technical term I believe was 'lost his marbles')