dear  theysayimmean 
         your  sister probably suffered  from post partum blues, it generaly occurs in 20-30 % females after birth of child, symptoms like , lack of intrest , loss of appetite, loss of sleep, anxious,  
           symtom like  burning in arm n legs due to low potassium,blurrin of vision due to 
high blood pressure, for her 
depression  u should give her assurance, good attechment  with baby, protein suppliment. w3 fatty acid n multivitamins.
for her blood pressure  u should start 
SPIRONOLACTONE 25 mg twice a day for 5 days .
This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: no urine output (
anuria), severe kidney disease, high blood potassium (
hyperkalemia).