Is there anything else a swollen side of my breast could be other than mastitis or a clogged milk duct? I've been breastfeeding 10 weeks now and had a clogged duct once early on and it was pretty easy to massage out. I have a little bit of a knot this time on the side of my breast but it's really hard and sore on the whole side. I've tried heat and massage and nothing is happening. He feeds regularly from both sides. This has just developed in the last few hours but it's extremely painful and I'm not sure what else I can do.

EDIT painful hard side is as big as my hand now SOMEONE PLEASE HELP ME