I don't copy paste my bids, so read through please. It'll enlighten you.
Many reasons why your virtualized server is at 100%
1. Malware, eating up your PC's CPU and Network to DDos other networks/hosts
2. Malware, transferring you DB and extracting client info for own benefit.
3. Unpatched versions of SSH and Apache/nGinx.
and most of people I know who faced this, never kept a log of how's their >Virtual server behaving over time.
I faced this issue with my GoDaddy and AWS sites, found it to be malware. But before i cleaned, I found out WHO let that in. That is the most interesting part for person like me. LSOF.
I'll do it, in due time