Soreness in the breast and nipple can be due to multiple causes like,
Inflammation in breast tissue,
breast cancer, hormonal imbalance, pregnancy, fibrocysctic breast changes,
cervical radiculopathy, inflammation of the
cartilage connecting breast bone and the ribs, inflammation of the superficial breast veins due to clot, any injury to breast.
In your explanation you have doubt can it be due to pregnancy?. I suggest to do a pregnancy home test and check if its positive yes it can be due to pregnancy. But if its negative then I suggest to meet your gynec doctor for proper check up and treatment.
Now next is about your pressure pain in morning, it could be because of
stomach upset or
gastritis also. I suggest to check with doctor on this too if pregnancy test is negative.
I suggest to follow above steps and do some changes in life style like have good healthy different fruits and vegetables, do regular exercise and take proper sleep for better health.
Take care.