This thread may get moved Hastelloy because I think you should have put it in the tech section.
Open your browser and look for any add-ins or extensions you don't recognise. Before answering the what do you want to do next , open task manager and look for a running process you don't recognise. Look in add/remove for anything you don't recognise. Run adwcleaner. Run Malwarebytes to see if it finds anything suspect , if it does then do repeat scans until it finds nothing , you have to do repeat scans cos Malwarebytes does not always remove all individual segments of something on the first pass.