Blue veins on breasts

Went to go into the shower when my husband jumped back and went “woah!”. He pointed out that he could see really prominent blue veins on my breasts. I looked in the mirror and he wasn’t wrong - I’ve never had blue veins so bright blue before show up like this!

What would be the cause of this (ruling out pregnancy - I’m 33 days late on my period but both pregnancy and blood tests came back negative)? Breasts have also been suuuuuppppppper sore for the last five weeks to the point that I’m popping pain killers for them