It's likely nothing but it's worth getting checked out. I was a lifeguard and worked outside in my 20's and didn't think anything about it, but as I'm finding out all the damage you do to your body in your 20's comes back to kick your ass in your 50's. I only went in to get checked out because my wife was nagging me over a mole on my back. The one on my back was nothing but the one on my chest was cancer -and that diagnosis scares the shit out of you, you'll never realize how many cancer commercials there are on TV until you have it, ugh. Treatment is pretty straight forward they just cut it out, it doesn't hurt the worst is just waiting for the biopsy to get analyzed. The only advice I can give you is to get it checked out, you'll feel a lot better when it's taken care of.
> you are terrifying me
If it’s just enough to get you to the dermatologist and then stop, count it as a blessing.