my sister is little bit careless about her health. she delivered baby in 26 november 2012. she has been waken up (rarely slept) all the nights and day time while taking care of her child. now many problems are being seen in her body.
1. she feels pain in her knees and sometimes swelling.
2. her belly has been increased in size and tightening, looking like pregnant.

we will go for checkup to doctor.
what may bee the problem, can you please tell me reason, further precautions and level of danger about these symptoms.