It might be malware/adware.  Download, install, and run the excellent freeware program Malwarebytes, available from here:
	
	
		
			
				
			
			
				
				Download free antivirus: easy install for all devices. Remove unwanted malware like viruses, ransomware, spyware & more.
				
					
						
							
						
					
					www.malwarebytes.com
				
 
			 
		 
	 
It does a very good job of removing adware/malware.