It could def turn into mastitis, try hot shower, I almost got it 2 weeks ago after 11months of bf, my daughter started to drink less efficiently and a blocked duct ( which I had gotten twice before) turned into a bad episode of teeth shattering chills, a sore breast and burning skin and redness on the area that hurt. I pumped: nothing, it go worst and I really felt worst my body started to hurt everywhere. Then I got in the shower and aimed the hot water directly at the affected area an massaged as much milk out as I could for about 15 min, and it was gone, the symptoms all went away one by one, but it was a sample of how bad mastitis can get. You need to fix it before it gets serious and if for some reason u can't dont wait to call your doctor.