Can a suit be filed for Medical negligence if a person becomes hospitalized due to lack of proper medical care?

My 70 yr. old Father in Law has a spinal injury from a fall on March 9th and is now paralyzed. He was sent from a Hospital to a nursing/rehabilitation facility for PT on March 15th. March 17th at approx. 0430 he is transported to ER for high fever, and unresponsive. He is diagnosed with a bed sore. Approx. March 20th he is returned to same nursing facility. April 22nd he is transported to ER for high fever, unresponsive at our request because the facility Doctor was not responding to staff. He is diagnosed with 104.6 temp., low blood pressure, pneumonia, elevated kidney levels, massive infection in blood stream, two bed sores in poor condition, non responsive, urinary track infection and by ER's admission "extremely poor hygiene". The nursing facility started pushing for him to switch his insurance coverage from Anthem and Medicare to Medicade. When he refused, they began neglecting him by a nurses admission that he is checked on about every 2 to 2.5 hrs..