Thanks for your query.
The breast changes that you describe are normal - as soreness is not a persistent or reliable symptom of pregnancy
However the cramps you are getting are not normal, and you should visit your gynecologist to rule out chances of a threatened miscarraige.
Also, at 6 weeks, you should be getting your transvaginal ultrasound
scan to confirm the pregnancy and for dating, and to see that the pregnancy is viable.
Alongwith that, you can have an examination to know the cause of your cramps and pain.