It's because of chewing pressure caused dislocation of that rct treated tooth causing the trouble.
Please details required to prescribe medicines as you have hives as a allergic condition .
In the meanwhile you can rinse with lukewarm salt water after every meals and maintain oral hygiene by brushing with ultra soft toothbrush 2 times daily on a regular basis to prevent further loss of tooth substance due to caries.
Next Steps
consult online through Practo for further clinical information about it. We are here to help you!
Health Tips
1.apply ice pack EXTRAORALLY to the swelling area & don't apply any hot stuff.
2. don't chew anything hard from that side till the treatment is done.
Thanks!