Vein appeared after nipple piercing

Hey everyone! I got my nipples pierced professionally four days ago. They're still in pain a bit and I noticed tonight when I was cleaning them with water and antibacterial soap, that a large blue vein has appeared on both breasts, running towards the piercings. I don't believe they're infected, though one of them is bruised from the piercer messing up a little from not getting the barbell all the way through at first 😒. I'm just wondering what the blue veins mean??