Compromised Machine

If you've gone to Finder-->Applications and looked closely at all the apps there, and don't see anything unusual that you've not installed, the next step I could suggest is going to Etrecheck.com and downloading/installing/running the free version of the app.

Some tips for Etrecheck:

• Allow full disk access when you run it, as it provides a more complete report.
• Etrecheck is a completely safe app that doesn't disclose any private information, and doesn't run in the background when you're not using it. It was written by a frequent contributor to these discussion groups, and has proven invaluable many times when folks are puzzled by things going on with their Macs.
• Rather than try to decipher the report yourself, I'd suggest copying the entire report to your Clipboard, then pasting it here in your reply by using the Additional Text feature (3rd icon from the right in the bottom of the Reply window).

Once you've provided your Etrecheck here, we'll be able to examine it for you and see if there's anything amiss that might cause issues.

Hope this helps.