Oh gosh! Your phone has a mind of its own. This isn't something that is commonly reported with the LG L90. Since this is happening, when you receive a phone call are you able to hear the caller through the earpiece of the phone? If you plug headphones in and then unplug them again does the icon still stay on the screen?
Sometimes this can happen if dirt or lint get into the jack? I've read multiple reports of this happening different make/models of phones and users are able to get it back up and running after giving the audio jack a good cleaning.