Get your moles checked.
My dad died in July 1996 from a nasty mole on his back. He would ask me to scratch his back and I remember being 8 or 9 years old and having to scratch around it as it was near the seam of his tank top (which likely aggravated it daily). And would make comments about it being "gross". We just didn't know what we know today.
He was drying off after showering one morning and got blood all over the towel from the mole. He went to the dermatologist and was told he had malignant melanoma. This was in September 1995 and he was in the ground before the middle of July 1996. Nine months to get his affairs in order. I remember driving around and seeing his old college pals (one of which I still see once a year or so for lunch to this day). I remember him buying a bag phone, a "car phone" so we could keep in touch as he drove from Eastern KY to Duke University for experimental treatments (I believe it was the one that led to the immunotherapy treatments used today). He told my mom even if it didn't help him he hoped it would help someone.
I avoid the sun with the exception of the back of my neck and the top of my hands. He has no clue (nor do the dermatologists) what caused it but, like other posts mention, likely sunburns in childhood.
I am so hopeful for this treatment and thankful for the progress made on the immunotherapy fronts.