It's actually quite common because of the inflammation around the root tips. Most of the time, the symptoms will get better and disapper later. To help for now:
try not to chew on something hard/chewing/crunchy/sticky; take Ibuprofen/Motrin/Advil 3 pills a time, 3 times a day, after meals but not more than 7 days; talk to your dentist/endodontist about your concerns.
Please stop the medications if stomachache or blood streaks in stool and seek dental service right away.
Good luck.