Unexplained Data Increase

My account is now showing our data usage at 1209 GB Used for this billing cycle (mid month), double our normal monthly usage, and the billing cycle is not even done yet?

Nothing in our home has changed, my son does online games, chats online, watches YouTube videos and uploads a YouTube video as he has been for months.  We have not added or removed any devises in our home, we have 2 computers, 2 laptops, 3 iPads, 3 cell phones and 1 Smart TV. We do not have all these devises running but they are connected as they have been for years.

Before this billing cycle, our average monthly usage was always under 675GB per month up until this billing cycle, I have never received any notifications concerning data usage, EVER!

I also received the following email today at 1:22 PM, claiming to be from Cox:

Email Validation

Hello Dear ,                                                                                 

It looks like You've recently changed your email password, We've disabled   
 your User ID and  Password to protect your confidential financial information.  (I have not changed my password}

You only have one more step - you're almost done! Click Continue below to validate your email address.

On Dec 14 I received an email claiming to be from (Ann) Cox Alerts as well, stating that I needed to verify my account, I did nothing, now the email content has been deleted.

Add so it's clear, I have ran multiple virus, malware and ransomware scans on all my devices using Kaspersky, Norton and Microsoft's Security Scanner. (no Issues have been found)

On Dec 4, I received an email claiming to be from Cox Customer Safety, claiming that Cox has identified that one or more of my computers behind my cable modem was infected with the Zeus Trojan/Bot, also known as Zbot.

In the email it provided links to what they claimed to be Microsoft link to the Security Scanner and one for Symantec's website, I did not click on any of the links, I went directly to their secured websites for support and run their scanners. No issues were found.

Below are the current data usage being recorded, I have upped my data package to unlimited to avoid overage charges, please advise if this is a system wide issue on Cox end or if I need to take serious actions on my end.

Nov 18 106GB *
Nov 19 143GB *
Nov 20 75GB *
Nov 21 17GB
Nov 22 8GB
Nov 23 10GB
Nov 24 106GB *
Nov 27 97GB *
Nov 28 106GB *
Nov 29 148GB *
Nov 30 4GB
Dec  1 19GB
Dec  2 5GB
Dec  3 84GB *
Dec  4 113GB *
Dec  5 17GB
Dec  6 11GB
Dec  7 50GB *
Dec  8 16GB
Dec  9 86GB *
Dec 10 7GB
Dec 11 14GB
Dec 12 16GB
Dec 13 11GB
Dec 14 11GB
Dec 15 92GB *
Dec 16 137GB *
Dec 17 6GB