Severe internet spikes/fluctuations

[TheBrentLee]

My internet spikes fluctuates so badly that It renders anything I do that is related to the internet useless. I called my ISP and there's nothing wrong on their end. I also have 2 other computers and this one is the only one that has this problem. Here's an example:

 

[Emerald]

have you checked your computer for malware and virus?