I Donated Blood, And Within A Day Later I Got

I donated blood, and within a day later I got a red dot under my skin, 2 months later it got bigger. A month later from that little dots appeared around it. Its no longer red just a little darker from my skin color. But at times it is red as if it was irritated. The skin that has the dots is soft. But doesnt itch. Its already been a year since I've had it. What is this?