My sister in law misscarred back in august and then again about 5 weeks ago but 2 days ago she took a pregnancy test and it was a faint positive and she was shocked bc it took her 8 months to get pregnant again the first time she miscarried so she waited until the next morning to take another test and it was negative so she's not sure if she is really pregnant. Could she still have hcg in her system from her last pregnancy?