Sore breasts, nausea and vomiting could be pregnancy signs. It is not clear from your question whether the discharge is from nipples or from vagina. If it is from vagina, this could suggest non-viable baby inside the uterus trying to get aborted (Missed abortion). If it is from nipples, the chances of pregnancy are very high.
However, very scanty period 2 weeks ago is a tricky issue. If it was a real period, you cannot be pregnant and the breast changes and nausea, fatigue, etc. could be due to birth control pills. To me, this looks to be the most possible cause.
However, you may get ultrasonography done to rule out the pregnancy.
If it turns out to be missed abortion, then urgent termination has to be performed lest serious complications like serious bleeding due to bleeding disorder. Your Obstetrician will take care of it.
Now do not waste time and go to Obstetrician.

Hello, and I hope I can help you today.

All the symptoms you describe can be caused by side effects from the birth control pills themselves, which are similar to symptoms of early pregnancy. I do not know what issues that led you to discontinue the pill, or which one you take now, but nausea and headaches are common side effects, as well as irregular bleeding or spotting. Dark discharge is just very slow bleeding mixed with normal vaginal fluids.

Usually these symptoms resolve after 3 months or so on the pill, but everyone tolerates different brands differently. If you have been taking the pill every day, you should be protected against pregnancy, but if you still have these side effects after the third month, I suggest you see the doctor back who prescribed that brand of pill for you to suggest alternatives. There are hundreds of birth control brands on the market today and some hormonal methods which are not pills, which can sometimes be helpful in patients who get nauseous from oral contraceptives.

I hope this advice was helpful and answers your question.

Best wishes, Dr. Brown