as per the information provided by you it seems that there is inflammation in your gums
and that's why you are having this feeling.
you haven't clarified as to why you took the painkiller but your feeling of blood in your mouth has nothing to do with it.
just see a dentist
and let him see what exactly needs to done .
the sore mouth is another sign of inflammation so removing the calculus and plaque
from your gums will fix everything.
don't worry and visit a dentist soon