The reason your belly is so sore is from streching ligaments and they can hurt bad and get worse when you sneeze and strech and stuff as for your breast Im not sure what helps I havent found something to help me yet. Good luck.
Its the lovely hormones of pregnancy! The belly pain is the baby growing! It gets better it don't go fully away but u get use to it after a while and just don't notice it as much! Congrats and good luck!