I can relate to this. My step father died primarily because of DVT and Pulmonary Embolism on the lung. He became more confused and sounded bad with pneumonia infection. I even complained to the hospital (rest - bite centre) I am convinced they did not have the correct drugs of facilities in this place to help him along even though his Bladder cancer had metastasized to the left Adrenal gland at least. CT scans shows something on his spine but this was never biopsied. I bet they never used Anticoagulants or compression stockings despite having symptoms for this condition. He was at risk anyway of this ailment due to the cancer and mobility issues  spending the last 5 weeks of his life in hospital!. life is cruel! I wonder if he would have survived longer had he been at home! That though haunts me to this day! Sorry for your loss as well! A PALS enquiry is taking months! It is worth doing if you would need some closure or to highlight negliegence if applicable