My mom went to the hospital on tuesday with abdominal pain and they diagnosed her with a uti and sent her home?

With antibiotics. On Friday the abdominal pain came back and she went back to the ER and they said that she had a bad uti and started IV fluids and antibiotics. They admitted her and she stayed until she died on Sunday. My mom stopped producing urine and I was concerned and asked the doctor about it and he told me that she was not producing urine because her electrolytes were all over the place, but that everything would get better soon. My mom had chronic heart failure and had a defibrillator implanted, but the hospital felt that it was not a concern that they should monitor. They also could not find a pulse the day before she passed away but they did not have her hooked up to any machines. When my mom died all she had was an IV line and nothing else. I feel that the hospital failed to follow hospital procedure. The death certificate says my mom died of septic shock. I want someone to look into the death of my mom. Any advice?