My recommendation is to buy (or set up) an internet router with software which will monitor your own traffic.
For example, I use a linux machine with bandwidthd as my router, which allows me to monitor my usage.
As a "Computer Programmer with a BA in Business Information Systems and Seven Microsoft Certifications including MS Professional and MS Specialist as DBA", I would expect you would have already done this, so you could give us some hard statistics, before coming on the forum.
There are several very well known hacks for various internet-accessible security cameras. It is entirely within the realm of possibility someone is running a botnet on your cameras, for example.
