Memory usage keeps going up to 67% and back to 24% continuously

[DCxtreme]

I noticed that my ram started going crazy without even having any apps open. It goes all the way up to 67% and falls back to 24%, and again, like a rollercoaster. It shows that windows defender is using most of it but, I'm not scanning or nothing with it, I even opened it to check it. Here is a photo (I'm pasting the link because I don't know how to make it appear here) http://imgur.com/a/sZd5X

Do you think it is a virus... Or just a bug?
I'll keep my eye on it.
Any help is appreciated!

Quick update:
So right after writing this I have checked it and disk usage is now 0% and ram usage seems normal, I keep looking at it and it seems like it has stopped.

Is there a problem or was it just a bug?

 

[geofelt]

The app was using 100mb, a small fraction of perhaps 16gb.
Not a problem.

 

[DCxtreme]

The app was using 100mb, a small fraction of perhaps 16gb.
Not a problem.

Yes but the total memory usage was 67% take a better look

 

[geofelt]

The app was using 100mb, a small fraction of perhaps 16gb.
Not a problem.

Yes but the total memory usage was 67% take a better look

I read that to say that of all the memory in use, 67% was for the app while it was running.
The other 33% was used by other apps at the time.
It is only a fraction of the total ram.