Hello , Good morning.
Bipolar has a tendency to reoccur at time of pregnancy or post delivery period. May be she has encountered an episode of Depression.
Post partum psychosis can also be a possibility.
Since she is feeling to infant, an extra caution has to be taken in prescribing drugs . Some drug s has tendency to pass on in mother's milk into the child.
Next Steps
Consult a Psychiatrist or Neuropsychiatrist of ur choice and discuss all symptoms in detail , plan a treatment that suits her heath , current situation and to baby health.
Health Tips
Don't panic or fear, just follow the instructions of ur Psychiatrist ,she will recover .
Take care.
** Have a safe & peaceful day **