Hi Genna,
  I worked with a mother with a similar story.  She had large breasts and we
suspected the weight of them was compressing something that would trigger
intense pain two or three times a day, throughout the entire pregnancy.  The
only was she could stop the pain, which would last 20 minutes, was to squeeze
her breasts, very forcefully.  Her nipples would turn white then purple during
these episodes.  Luckily, the pain went away once the baby was born. So there
must have been some hormonal connection as well.  Does vasoconstriction sound
correct?
Lezlie Densmore
LLL of Chicopee/Springfield, MA