My 84-year Old Father Fell On Monday. By The Next

My 84-year old father fell on Monday. By the next day, his lower back was bothering him. He called his doctor on Wednesday but only told her that his lower back was sore, not that he had fallen. She put him on a muscle relaxant which was probably too strong for him. My mother called the doctor the night before the hurricane and his medication was changed to Tylenol. His back is still sore and they will speak with the doctor again on Monday. In the meantime, is it too late to use ice or heat on it? If it is not too late, which one should be used?