Suggest Treatment For Stippled Greyish Patch On Skin

Hi Doctor,
I'm a 19 year old Caucasian women. Today after I took a shower I noticed that I needed to put cream on my upper right arm. So I did and once it was rubbed in I could see that there was a slight discolouration on a small patch of my skin. It's like a stippled greyish colour with a lighter than normal small patch of skin underneath. It's only on one spot that I've seen and it's only become apparent to me today. I don't know if it's anything to even worry about. Thanks!