Unknown SQS message creation

I'm having an issue where I have a lambda function triggering off an SQS message, and something seems to have gone rogue and I can't kill it. I need to understand what's causing the SQS messages to get created, and my attempts to debug haven't resulted in anything yet.

Current known things:

• I've completely killed my client (localhost, since I'm in development mode), so nothing should be initiating new calls. In fact, the last record of calling the API that creates SQS jobs was triggered hours ago. That function does not have any loops in it.
• Monitoring in SQS seems to indicate that messages are being added to the queue ~8 times/minute
• From the logs that my triggered lambda function is sending, it looks like those messages were initiated from client calls that happened hours ago.
• I've tried looking for SendMessage and SendMessageBatch in CloudTrail, and I can't seem to find those records, so something is off there, but I've tried creating a new trail with all management events, and nothing is showing up

I'd really like to see if I can find more information about what's causing the SQS queue to get called so many times. Any pointers are appreciated.