pregnancy signs after a miscarriage

My girl friend and I had intercourse five to seven days before her period. She had a normal period. A week later she started spotting and cramping. This lead to full bleeding with large clots the size of quaters. The bleeding stopped for a few hours and came back. She also experince extermely bad cramps then too. She went to her Family doctor who did a pelvic exam, a urine pergancy test and a blood test. The doctor sent my girl friend for a transvaginal ultrasound. The results of the urine test were negative, the ultrasound didnt show anything in the uterus, the ovaries were the same size and the endometrial strip was thin. She contacted the doctor about the blood test results and was told the results were normal.

She visited her OB/GYN and he told her that he was 80%sure she had had a miscarriage. That was 28 days ago, we have not had intercourse again, but now she is showing signs of pregnancy. She has had nasuea, a sinus infection, and now her breast itch and when they are exposed to cold temperature they leak.

Are these signs that she is pregnant or could these be from the hormone imbalance due to the miscarriage.

She takes the medications Welbutrin xl and Lexapro

Thanks for the info