It's not a virus, because a "virus" is a specific type of malware capable of propagating itself, which doesn't exist for the Android platform. Malware on Android is usually of the "trojan" type, i.e. hidden inside or disguised as a legitimate app in order to trick the user into installing it.

That wasn't just a pedantic point: if you have a malware infection it means it's one of the apps you installed that is the source (or, if you are really unlucky and have a cheap Chinese device, it may be pre-installed by the manufacturer). So the solution is to identify which app and get rid of it. Did this start at a particular time? If so, any apps you installed or updated in the week or so before that are suspect. Apps downloaded from unofficial sites are much more likely to be the source, so look at those too.

If you are really unlucky and have an old enough device malware may be able to install itself to /system, making it impossible to remove without reflashing the device. But hopefully that's not the case here.