As little as possible. Bumps that appear that fast are almost never a problem, especially when they get smaller as you say yours did. Picking won't change anything one way or another, so you don't need to feel bad about that.
My advice is to just leave the area alone--it's probably a blocked follicle. If it's still there in 2 weeks, show it to a doctor. But melanoma is not the least bit likely.
Best.
Dr. Rockoff