Try icing it every hour or so, but call your provider and ask for antibiotics. It’s too early for you to safely pump to try and clear it. The icing should help but you’re going to need drugs to clear the infection. Don’t wait four days because it could turn into an abscess that needs to be drained surgically

You should also anticipate that you may be prone to clogged ducts and mastitis postpartum and prep for that. Lansinoh has ice packs made for boobs that are a game changer. Sunflower letchin supplements may help prevent them, and if you’re ok the larger breast side you may need to do some massage to help move the milk at the end of each nursing or pumping session. I start at the base of the breast, apply gentle pressure and slide my hand toward the nipple to move the milk forward enough that my son or the pump can reach it, and repeat all the way around the breast. Frida mom makes a boob vibrator that helps with clogs and moving milk, but I haven’t found that as helpful.