I have black spots on my iPhone screen

2 days ago I dropped my phone on accident and I didn't realize so I accidentally stepped on it, when I picked it up it had a few black spots in the screen. also I dropped it outside whole it was raining so could it be water damage or is it just from dropping it? yesterday the spots would slowly move, when I put my phone in my pocket there would be a big spot on one side but then I'd take it out and there would be 2 spots on each side. does it sound like water damage? is there anything I can do to fix it?