Sounds like you have some malware on your computer. There are quite a few free malware scanners that you might want to try and see if it helps. I use malware bytes. I've used the free version many times and found it to work great. Here's a link. Others may chime in with other programs. Several out there that should do the trick, but this is the one I use. There is a premium version, but just download the free version and run it. 90% of the time in situations similar to these, it finds and cleans out the problem.
Here's the link: https://www.malwarebytes.org/