I am sorry to hear about your daughter. The blood clots that the doctors have detected are probably located inside the uterus. It so happens that during the pregnancy, the placenta remains attached to the inner surface of uterus (endometrium). After the delivery, the placenta comes out and so does the endometrium too eventually as the uterine blood vessels cut squeeze and cut off the blood supply there and the uterus contracts to squeeze it out. As a result, the remaining portion of the endometrium comes out in the form of bleeding. But if some amount of placental tissue remains adherent, it might not easily come out and the uterus contracts repeatedly trying to expel it, thus causing the pain for which she needs to be given pain medication like morphine. These are the blood clots that the doctor is talking about. These could have got infected, causing the fever. For the infection to subside, the blood clots need to come out, which would probably happen on its own. Antibiotics and paracetamol are required. Since the blood clots are not inside a blood vessel, the chances of dislodging and travelling is unlikely.