My friend Jessica she too afraid to ask

But she had miscarriage a year ago then last week found she pregnant but today had bad cramping n started bleeding she informed her Dr who knows the history she asked what can cause two miscarriage she has one living child

Does she need to get checked or tests she only 24 if that matters. Does it happen often ,could there possibly be an issue any similar story's she wants feedback she uses this app but she feeling low. Just trying help my friend out