Pinging Randomly

Everytime I'm playing League of Legends normally, my mouse just starts pinging out of nowhere. It as if I was pressing always ctrl or shift, it can be all type of pings and it mostly happens when I level up. I have already reported this to Riot twice and didn't got an answer. My keyboard doesn't do that in any other game or anything at all. To make it stop sometimes I have to minimize League of Legends and re-enter it. I really don't know what to do and I have already searched for the solution everywhere...

In the Video, you can see that I ping in the beginning then I was going to minimize but I killed Lucian and then I went for it. In the end of the video you can see that I pinged again.