So...I'm really scared. About half an hour ago, I just put my hand on my shoulder and I felt a big, soft bump. I never felt one there before so I touched it more and it suddenly popped and some liquid started coming out. I looked in the mirror and saw a tinier bump replacing the big bump (I guess it was inside or under the big bump). It's within a circle of light colored skin (I have tan skin) with red outlining it. Now, the place where the big bump popped hurts, kind of like that feeling you get after scraping your knee.
I have no idea when that bump started forming or how that mole got there. I never felt or saw it there before. I don't go out in the sun too much but when I do, I make sure I put on sunblock all over and at least 30 minutes to spare until sun exposure (I'm really paranoid about getting skin cancer). I'm Asian and I have tan skin, so I know I'm not as likely as a Caucasian girl with fair skin to get a cancerous mole.

What could this be??