Red and blinking areas on Mac

I have MacBook Air, 13 inches, macOS Sierra. Version 10.12.5

Sometimes when I put mouse over or click on some text - the area where mouse pointing getting red, sometimes this red area is getting bigger and started blinking and looks like those changings on screen are nor related to mouse.

It happened once a week and I could not tell what trigger this. I was told by Mac representative that this is probably some sort of malware.

But I have application Adware Medic and it doesn't detect any malware.

I think that it is possible hardware issue.

Any suggestion what cause this issue and how to fix it?

thanks.

//EDITED Sometimes I have no red (see pictures below):

Solution 1:

You may be able to run some diagnostic tests yourself if you follow the Apple article How to use Apple Diagnostics which also includes a link for machines introduced before 2013.

Worst case scenario: you have a graphics card issue. The in-built diagnostic tests may not be able to give a definite answer. An Apple Store or authorised repairer can diagnose this.

Before assuming the worst, I would recommend backing up your machine, running some diagnostic tests, and if you find no problems try re-installing the operating system. It is possible that re-installing your non-Apple applications one-by-one may reveal the culprit.