From the top output it does show you have a lot of apache stuff and they are all doing something since it also appears that msyql is running pretty hard too. So your system IS doing something.
What is going on at the time this snapshot was run? Were you deploying? Do you have a large campus where you have a lot of devices talking back to the fog server?
/var/log/httpd/access_log and /var/log/httpd/error_log might give insight on what is hitting your apache server.