Hard breasts, loss of color in nipple

Emma
Hi everyone, 
I am 21 weeks. I woke up this morning and my breasts were hard and my nipples were leathery and hard, but also they were the same color as my skin tone, maybe even paler. They are usually a deep pink. I massaged them for a few minutes and that seems to help. It was really weird, anyone else experience this? Maybe I cut off the blood flow when sleeping on my side?