I had a miscarriage and became pregnant after it and I was terrified the entire time, even after the 12th week (when the chances of
loss go down). Bleeding in early pregnancy
can be fine.
Signs to look for include bright red blood, clots, lower back pain accompanying cramps, fever, etc.
Cramps and lower back pain are a normal pregnancy symptom, so do not worry about that unless it is accompanied by the other symptoms listed. I truly hope she is not miscarrying!