OP is very misguided. Cloudflare does not proactively refresh their caches. That's just not how CDNs work.

Here is how I would troubleshoot:

1. Look for the X-Forwarded-For header: All requests or the AWS server will come from Cloudflare. That's the point of a CDN. The X-Forwarded-For header tells you the actual client IP making the request. I think Cloudflare has some tools to block certain IP addresses. You can use that once you have identified the IP to block.

2. Make sure nginx returns appropriate headers so that Cloudflare will cache the responses from the origin server. If caching is set up correctly, Cloudflare will not make requests to your server. They will serve from their cache instead.