I get a strange red lumpy spot on my boob every few months, it appears over night and is very red and large - maybe 3cm across (I have big boobs!), lasts for about a week and gets worse before it gets better. The skin where the spot is feels thick rather than a definable lump. I have a good squeeze check it out but there is no head and I can't draw one out with a hot compress. When it does go it leaves a reddish patch on my breast, almost like a scar.
I don't have a temperature or feel unwell when I have the spot, although the spot itself feels very warm.
I get them on both breasts (always around the same area though) which make me think it is fine but this last one was so very big I got a bit freaked out!