Hello sir...
Get x-ray (IOPA) of that Root canal treated tooth done to check any re_infection in the root canal treated tooth...
Get OPG also done to check for any wisdom teeth...
sometimes due to wisdom teeth, pericoronitis and gum bleeding can also occurs...
if there is re_infection in root canal treated tooth, then do re-rct in that...
If there is presence of wisdom teeth then get that tooth extracted surgically
Next Steps
kindly visit dentist for curthur consultation and management