i dont know what it is it may be water or moisture under the screen but i have no idea how it got there since i have not dropped my phone or even got it slightly wet. this issue started after i got my phone screen repaired for ?40 which is a good price for a decent screen. whenever i put my phone in my jeans pocket they would get this on the screen sometimes it lasts for 1 day sometimes hours this time its been 3 days and im getting worried. i've tried using a fan and hair dryer but its not working. im going to post a picture to help you see what it is.