What Could I have Done Differently?

My Guinea Pig sow died Saturday from childbirth. I'm not sure exactly how old she was, but my guess is 7 months or so. She had two still born pups on Friday night at 9:30 pm- they were obviously under-developed because they had no hair, fused eyelids and ear buds that were not fully formed. After she had them, I removed them from the cage to let her rest...but I saw no blood, placenta or cords of any kind. The next day she was lethargic and obviously in pain. I noticed some bloody discharge in her cage. I wrapped her in a towel and put a hot compress on her to try to induce the discharge of the placenta and rubbed her belly gently. She seemed septic already and was shivering, and I though of giving her infants tylenol susp.-but I didn't want to give her anything that could damage her liver. My only thought was if the placenta didn't come out, or another pup was in there...she would die of sepsis. So, I put gentle pressure on her belly right above her vagina and held onto the cord coming out of her, but didn't tug or pull...yet she died on my lap after about a minute of trying at around 4pm, less than 24 hours after giving birth. I find it hard to believe she was that septic already. Was it me pulling the cord? Maybe the babies were dead for awhile and she was septic from that to begin with? I have no experience with this and her widow will remain alone because I DO NOT want to deal with this again. Does anyone have any input? Is this common?