I am ten weeks pregnant and my breast all the sudden stop being sore is that a bad thing?

Not necessarily: Breast symptoms in pregnancy tend to be unpredictable. Unless you have symptoms of significant pain, a newly discovered mass, or dicharge, just keeping your doctor abreast of things (pun intended) should suffice.

Check the pregnancy: A sudden loss of pregnancy symptoms, like breast tenderness, could indicate decreasing hormone levels and a miscarriage, even if you are having no pain or bleeding. On the other hand this could also be completely normal as you get farther into the pregnancy. A pelvic sonogram (ultrasound) would be the quickest way to confirm that everything is ok.