What Causes Vaginal Spotting And Mild Cramps Along With Delayed Periods?

Hello, my sister had a abortion about a month ago due to medical problems she was 4 weeks pregnant.. 2 weeks after abortion she took a home pregnancy test and it was negative.. but she really wants to get pregnant again and was trying really hard to after 2 weeks of the abortion.. around the time that her period suppose to come she have light red spotting jus mild cramps n o tender breast or neusea .. do you think she could b pregnant again?