First, the RCT treated tooth should be retreated. The abscess will occur again. Depending on condition of tooth and bone, either it can be retreated with RCT or it can be better extracted , wait for 1 month and go with implants.
Next Steps
Please visit an Endodontist, take X-ray confirm the treatment option and then proceed.
Health Tips
Avoid chewing over that area. Continue bushing and flossing
Hope this helps