A certificate authority downloaded on my device

I have this weird stuff that’s been happening on my phone lately and it’s all signs of a virus or malware. I even called my phone provider to see what they say and they said they didn’t put it there and that it sounded like a virus or malware. It shows up in my notification bar when I pull it down on my Motorola phone. It has what appears to be a search engine of some sort and it says there’s been a certificate authority installed on my device for network traffic monitoring or modifications. What does this really mean and why isn’t my AVG Antivirus Picking It Up When I Scan It??? Someone if U can please help me with this I’m desperate wanting and needing answers but nobody has been able to help me yet!!!